Original release date: June 30, 2022

Summary

Actions to take today to mitigate cyber threats from ransomware:
• Prioritize remediating known exploited vulnerabilities.
• Train users to recognize and report phishing attempts.
• Enable and enforce multifactor authentication.

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), the Department of the Treasury, and the Financial Crimes Enforcement Network (FinCEN) are releasing this CSA to provide information on MedusaLocker ransomware. Observed as recently as May 2022, MedusaLocker actors predominantly rely on vulnerabilities in Remote Desktop Protocol (RDP) to access victims’ networks. The MedusaLocker actors encrypt the victim’s data and leave a ransom note with communication instructions in every folder containing an encrypted file. The note directs victims to provide ransomware payments to a specific Bitcoin wallet address. MedusaLocker appears to operate as a Ransomware-as-a-Service (RaaS) model based on the observed split of ransom payments. Typical RaaS models involve the ransomware developer and various affiliates that deploy the ransomware on victim systems. MedusaLocker ransomware payments appear to be consistently split between the affiliate, who receives 55 to 60 percent of the ransom; and the developer, who receives the remainder. 

Download the PDF version of this report: pdf, 633 kb

Technical Details

MedusaLocker ransomware actors most often gain access to victim devices through vulnerable Remote Desktop Protocol (RDP) configurations [T1133]. Actors also frequently use email phishing and spam email campaigns—directly attaching the ransomware to the email—as initial intrusion vectors [T1566].

MedusaLocker ransomware uses a batch file to execute PowerShell script invoke-ReflectivePEInjection [T1059.001]. This script propagates MedusaLocker throughout the network by editing the EnableLinkedConnections value within the infected machine’s registry, which then allows the infected machine to detect attached hosts and networks via Internet Control Message Protocol (ICMP) and to detect shared storage via Server Message Block (SMB) Protocol. 

MedusaLocker then: 

• Restarts the LanmanWorkstation service, which allows registry edits to take effect. 
• Kills the processes of well-known security, accounting, and forensic software. 
• Restarts the machine in safe mode to avoid detection by security software [T1562.009].
• Encrypts victim files with the AES-256 encryption algorithm; the resulting key is then encrypted with an RSA-2048 public key [T1486]. 
• Runs every 60 seconds, encrypting all files except those critical to the functionality of the victim’s machine and those that have the designated encrypted file extension. 
• Establishes persistence by copying an executable (svhost.exe or svhostt.exe) to the %APPDATA%Roaming directory and scheduling a task to run the ransomware every 15 minutes. 
• Attempts to prevent standard recovery techniques by deleting local backups, disabling startup recovery options, and deleting shadow copies [T1490].

MedusaLocker actors place a ransom note into every folder containing a file with the victim’s encrypted data. The note outlines how to communicate with the MedusaLocker actors, typically providing victims one or more email address at which the actors can be reached. The size of MedusaLocker ransom demands appears to vary depending on the victim’s financial status as perceived by the actors. 
 

Indicators of Compromise

Disclaimer: Many of these observed IP addresses are several years old and have been historically linked to MedusaLocker ransomware. We recommend these IP addresses be investigated or vetted by organizations prior to taking action, such as blocking.

MITRE ATT&CK Techniques

MedusaLocker actors use the ATT&CK techniques listed in Table 1.

Table 1: MedusaLocker Actors ATT&CK Techniques for Enterprise

Mitigations

• Implement a recovery plan that maintains and retains 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).
• Implement network segmentation and maintain offline backups of data to ensure limited interruption to the organization.
• Regularly back up data and password protect backup copies stored offline. Ensure copies of critical data are not accessible for modification or deletion from the system where the data resides.
• Install, regularly update, and enable real time detection for antivirus software on all hosts.
• Install updates for operating systems, software, and firmware as soon as possible.
• Review domain controllers, servers, workstations, and active directories for new and/or unrecognized accounts.
• Audit user accounts with administrative privileges and configure access controls according to the principle of least privilege. 
• Disable unused ports.
• Consider adding an email banner to emails received from outside your organization.
• Disable hyperlinks in received emails.
• Enforce multifactor authentication (MFA).
• Use National Institute of Standards and Technology (NIST) standards for developing and managing password policies:
  • Use longer passwords consisting of at least 8 characters and no more than 64 characters in length.
  • Store passwords in hashed format using industry-recognized password managers.
  • Add password user “salts” to shared login credentials.
  • Avoid reusing passwords.
  • Implement multiple failed login attempt account lockouts.
  • Disable password “hints”.
  • Refrain from requiring password changes unless there is evidence of password compromise. Note: NIST guidance suggests favoring longer passwords and no longer require 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.
• Only use secure networks; avoid using public Wi-Fi networks.
• Consider installing and using a virtual private network (VPN) to establish secure remote connections.
• Focus on cybersecurity awareness and training. Regularly provide users with training on information security principles and techniques as well as overall emerging cybersecurity risks and vulnerabilities, such as ransomware and phishing scams.

 
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-Multi-State Information Sharing and Analysis Center (MS-ISAC) Joint Ransomware Guide
• No-cost cyber hygiene services: Cyber Hygiene Services and Ransomware Readiness Assessment

Reporting

• To report an incident and request technical assistance, contact CISA at cisaservicedesk@cisa.dhs.gov or 888-282-0870, or FBI through a local field office. 
• Financial Institutions must ensure compliance with any applicable Bank Secrecy Act requirements, including suspicious activity reporting obligations. Indicators of compromise (IOCs), such as suspicious email addresses, file names, hashes, domains, and IP addresses, can be provided under Item 44 of the Suspicious Activity Report (SAR) form. For more information on mandatory and voluntary reporting of cyber events via SARs, see FinCEN Advisory FIN-2016-A005, Advisory to Financial Institutions on Cyber-Events and Cyber-Enabled Crime, October 25, 2016; and FinCEN Advisory FIN-2021-A004, Advisory on Ransomware and the Use of the Financial System to Facilitate Ransom Payments, November 8, 2021, which updates FinCEN Advisory FIN-2020-A006.
• 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.

Contact Information

To report suspicious or criminal activity related to information found in this Joint Cybersecurity Advisory, contact your local FBI field office at www.fbi.gov/contact-us/field-offices. 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. To report incidents and anomalous activity or to request incident response resources or technical assistance related to this threat, contact CISA at report@cisa.gov.

Revisions

• June 30, 2022: Initial Version

Original release date: June 23, 2022

Summary

Actions to take today:
• Install fixed builds, updating all affected VMware Horizon and UAG systems to the latest versions. If updates or workarounds were not promptly applied following VMware’s release of updates for Log4Shell in December 2021, treat all affected VMware systems as compromised.
• Minimize the internet-facing attack surface by hosting essential services on a segregated demilitarized (DMZ) zone, ensuring strict network perimeter access controls, and implementing regularly updated web application firewalls (WAFs) in front of public-facing services

The Cybersecurity and Infrastructure Security Agency (CISA) and United States Coast Guard Cyber Command (CGCYBER) are releasing this joint Cybersecurity Advisory (CSA) to warn network defenders that cyber threat actors, including state-sponsored advanced persistent threat (APT) actors, have continued to exploit CVE-2021-44228 (Log4Shell) in VMware Horizon® and Unified Access Gateway (UAG) servers to obtain initial access to organizations that did not apply available patches or workarounds.

Since December 2021, multiple threat actor groups have exploited Log4Shell on unpatched, public-facing VMware Horizon and UAG servers. As part of this exploitation, suspected APT actors implanted loader malware on compromised systems with embedded executables enabling remote command and control (C2). In one confirmed compromise, these APT actors were able to move laterally inside the network, gain access to a disaster recovery network, and collect and exfiltrate sensitive data.

This CSA provides the suspected APT actors’ tactics, techniques, and procedures (TTPs), information on the loader malware, and indicators of compromise (IOCs). The information is derived from two related incident response engagements and malware analysis of samples discovered on the victims’ networks.

CISA and CGCYBER recommend all organizations with affected systems that did not immediately apply available patches or workarounds to assume compromise and initiate threat hunting activities using the IOCs provided in this CSA, Malware Analysis Report (MAR)-10382580-1, and MAR-10382254-1. If potential compromise is detected, administrators should apply the incident response recommendations included in this CSA and report key findings to CISA.

See the list below to download copies of IOCs: 

• MAR-10382254-1 stix
• MAR-10382580-1 stix

Download the pdf version of this report: [pdf, 483 kb]

Technical Details

Note: this advisory uses the MITRE ATT&CK for Enterprise framework, version 11. See Appendix A for a table of the threat actors’ activity mapped to MITRE ATT&CK® tactics and techniques.

Log4Shell is a remote code execution vulnerability affecting the Apache® Log4j library and a variety of products using Log4j, such as consumer and enterprise services, websites, applications, and other products, including certain versions of VMware Horizon and UAG. The vulnerability enables malicious cyber actors to submit a specially crafted request to a vulnerable system, causing the system to execute arbitrary code. The request allows the malicious actors to take full control of the affected system. (For more information on Log4Shell, see CISA’s Apache Log4j Vulnerability Guidance webpage and VMware advisory VMSA-2021-0028.13.) 

VMware made fixes available in December 2021 and confirmed exploitation in the wild on December 10, 2021.[1] Since December 2021, multiple cyber threat actor groups have exploited [T1190] Log4Shell on unpatched, public-facing VMware Horizon and UAG servers to obtain initial access [TA0001] to networks. 

After obtaining access, some actors implanted loader malware on compromised systems with embedded executables enabling remote C2. These actors connected to known malicious IP address 104.223.34[.]198.[2] This IP address uses a self-signed certificate CN: WIN-P9NRMH5G6M8. In at least one confirmed compromise, the actors collected and exfiltrated sensitive information from the victim’s network. 

The sections below provide information CISA and CGCYBER obtained during incident response activities at two related confirmed compromises.

Victim 1

CGCYBER conducted a proactive threat-hunting engagement at an organization (Victim 1) compromised by actors exploiting Log4Shell in VMware Horizon. After obtaining access, threat actors uploaded malware, hmsvc.exe, to a compromised system. During malware installation, connections to IP address 104.223.34[.]198 were observed. 

CISA and CGCYBER analyzed a sample of hmsvc.exe from the confirmed compromise. hmsvc.exe masquerades as a legitimate Microsoft® Windows® service (SysInternals LogonSessions software) [T1036.004] and appears to be a modified version of SysInternals LogonSessions software embedded with malicious packed code. When discovered, the analyzed sample of hmsvc.exe was running as NT AUTHORITYSYSTEM, the highest privilege level on a Windows system. It is unknown how the actors elevated privileges. 

hmsvc.exe is a Windows loader containing an embedded executable, 658_dump_64.exe. The embedded executable is a remote access tool that provides an array of C2 capabilities, including the ability to log keystrokes [T1056.001], upload and execute additional payloads [T1105], and provide graphical user interface (GUI) access over a target Windows system’s desktop. The malware can function as a C2 tunneling proxy [T1090], allowing a remote operator to pivot to other systems and move further into a network.

When first executed, hmsvc.exe creates the Scheduled Task [T1053.005], C:WindowsSystem32TasksLocal Session Updater, which executes malware every hour. When executed, two randomly named *.tmp files are written to the disk at the location C:Users<USER>AppDataLocalTemp and the embedded executable attempts to connect to hard-coded C2 server 192.95.20[.]8 over port 4443, a non-standard port [TT571]. The executable’s inbound and outbound communications are encrypted with a 128-bit key [T1573.001].

For more information on hmsvc.exe, including IOCs and detection signatures, see MAR-10382254-1.

Victim 2

From late April through May 2022, CISA conducted an onsite incident response engagement at an organization (Victim 2) where CISA observed bi-directional traffic between the organization and suspected APT IP address 104.223.34[.]198. During incident response, CISA determined Victim 2 was compromised by multiple threat actor groups. 

The threat actors using IP 104.223.34[.]198 gained initial access to Victim 2’s production environment in late January 2022, or earlier. These actors likely obtained access by exploiting Log4Shell in an unpatched VMware Horizon server. On or around January 30, likely shortly after the threat actors gained access, CISA observed the actors using PowerShell scripts [T1059.001] to callout to 109.248.150[.]13 via Hypertext Transfer Protocol (HTTP) [T1071.001] to retrieve additional PowerShell scripts. Around the same period, CISA observed the actors attempt to download [T1105] and execute a malicious file from 109.248.150[.]13. The activity started from IP address 104.155.149[.]103, which appears to be part of the actors’ C2 [TA0011] infrastructure. 

After gaining initial access to the VMware Horizon server, the threat actors moved laterally [TA0008] via Remote Desktop Protocol (RDP) [T1021.001] to multiple other hosts in the production environment, including a security management server, a certificate server, a database containing sensitive law enforcement data, and a mail relay server. The threat actors also moved laterally via RDP to the organization’s disaster recovery network. The threat actors gained credentials [TA0006] for multiple accounts, including administrator accounts. It is unknown how these credentials were acquired. 

After moving laterally to other production environment hosts and servers, the actors implanted loader malware on compromised servers containing executables enabling remote C2. The threat actors used compromised administrator accounts to run the loader malware. The loader malware appears to be modified versions of SysInternals LogonSessions, Du, or PsPing software. The embedded executables belong to the same malware family, are similar in design and functionality to 658_dump_64.exe, and provide C2 capabilities to a remote operator. These C2 capabilities include the ability to remotely monitor a system’s desktop, gain reverse shell access, exfiltrate data, and upload and execute additional payloads. The embedded executables can also function as a proxy. 

CISA found the following loader malware:

• SvcEdge.exe is a malicious Windows loader containing encrypted executable f7_dump_64.exe. When executed, SvcEdge.exe decrypts and loads f7_dump_64.exe into memory. During runtime, f7_dump_64.exe connects to hard-coded C2 server 134.119.177[.]107 over port 443. 
• odbccads.exe is a malicious Windows loader containing an encrypted executable. When executed, odbccads.exe decrypts and loads the executable into memory. The executable attempts communication with the remote C2 address 134.119.177[.]107. 
• praiser.exe is a Windows loader containing an encrypted executable. When executed, praiser.exe decrypts and loads the executable into memory. The executable attempts connection to hard-coded C2 address 162.245.190[.]203.
• fontdrvhosts.exe is a Windows loader that contains an encrypted executable. When executed, fontdrvhosts.exe decrypts and loads the executable into memory. The executable attempts connection to hard-coded C2 address 155.94.211[.]207.
• winds.exe is a Windows loader containing an encrypted malicious executable and was found on a server running as a service. During runtime, the encrypted executable is decrypted and loaded into memory. The executable attempts communication with hard-coded C2 address 185.136.163[.]104. winds.exe has complex obfuscation, hindering the analysis of its code structures. The executable’s inbound and outbound communications are encrypted with an XOR key [T1573.001].

For more information on these malware samples, including IOCs and detection signatures, see MAR-10382580-1.

Additionally, CISA identified a Java® Server Pages (JSP) application (error_401.js) functioning as a malicious webshell [T505.003] and a malicious Dynamic Link Library (DLL) file:

• error_401.jsp is a webshell designed to parse data and commands from incoming HTTP requests, providing a remote operator C2 capabilities over compromised Linux and Windows systems. error_401.jsp allows actors to retrieve files from the target system, upload files to the target system, and execute commands on the target system. rtelnet is used to execute commands on the target system. Commands and data sent are encrypted via RC4 [T1573.001]. For more information on error_401.jsp, including IOCs, see [MAR-10382580 2].
• newdev.dll ran as a service in the profile of a known compromised user on a mail relay server. The malware had path: C:Users<user>AppDataRoamingnewdev.dll. The DLL may be the same newdev.dll attributed to the APT actors in open-source reporting; however, CISA was unable to recover the file for analysis. 

Threat actors collected [TA0009] and likely exfiltrated [TA0010] data from Victim 2’s production environment. For a three week period, the security management and certificate servers communicated with the foreign IP address 92.222.241[.]76. During this same period, the security management server sent more than 130 gigabytes (GB) of data to foreign IP address 92.222.241[.]76, indicating the actors likely exfiltrated data from the production environment. CISA also found .rar files containing sensitive law enforcement investigation data [T1560.001] under a known compromised administrator account.

Note: the second threat actor group had access to the organization’s test and production environments, and on or around April 13, 2022, leveraged CVE-2022-22954 to implant the Dingo J-spy webshell. According to trusted third-party reporting, multiple large organizations have been targeted by cyber actors leveraging CVE-2022-22954 and CVE-2022-22960. For more information on exploitation of CVE-2022-22954 and CVE-2022-22960, see CISA CSA Threat Actors Chaining Unpatched VMware Vulnerabilities for Full System Control.

Incident Response

If administrators discover system compromise, CISA and CGCYBER recommend:

1. Immediately isolating affected systems. 
2. Collecting and reviewing relevant logs, data, and artifacts.
3. Considering soliciting support from a third-party incident response organization that can provide subject matter expertise, ensure the actor is eradicated from the network, and avoid residual issues that could enable follow-on exploitation.
4. Reporting incidents to CISA via CISA’s 24/7 Operations Center (report@cisa.gov or 888-282-0870). To report cyber incidents to the Coast Guard pursuant to 33 CFR Section 101.305,  contact the U.S. Coast Guard (USCG) National Response Center (NRC) (NRC@uscg.mil or 800-424-8802). 

Mitigations

CISA and CGCYBER recommend organizations install updated builds to ensure affected VMware Horizon and UAG systems are updated to the latest version.

• If updates or workarounds were not promptly applied following VMware’s release of updates for Log4Shell in December 2021, treat those VMware Horizon systems as compromised. Follow the pro-active incident response procedures outlined above prior to applying updates. If no compromise is detected, apply these updates as soon as possible.
  • See VMware Security Advisory VMSA-2021-0028.13 and VMware Knowledge Base (KB) 87073 to determine which VMware Horizon components are vulnerable.
  • Note: until the update is fully implemented, consider removing vulnerable components from the internet to limit the scope of traffic. While installing the updates, ensure network perimeter access controls are as restrictive as possible.
  • If upgrading is not immediately feasible, see KB87073 and KB87092 for vendor-provided temporary workarounds. Implement temporary solutions using an account with administrative privileges. Note that these temporary solutions should not be treated as permanent fixes; vulnerable components should be upgraded to the latest build as soon as possible. 
  • Prior to implementing any temporary solution, ensure appropriate backups have been completed. 
  • Verify successful implementation of mitigations by executing the vendor supplied script Horizon_Windows_Log4j_Mitigations.zip without parameters to ensure that no vulnerabilities remain. See KB87073 for details. 

Additionally, CISA and CGCYBER recommend organizations:

• Keep all software up to date and prioritize patching known exploited vulnerabilities (KEVs). 
• Minimize the internet-facing attack surface by hosting essential services on a segregated DMZ, ensuring strict network perimeter access controls, and not hosting internet-facing services non-essential to business operations. Where possible, implement regularly updated WAFs in front of public-facing services. WAFs can protect against web based exploitation using signatures and heuristics that are likely to block or alert on malicious traffic.
• Use best practices for identity and access management (IAM) by implementing multifactor authentication (MFA), enforcing use of strong passwords, and limiting user access through the principle of least privilege.

Contact Information

Recipients of this report are encouraged to contribute any additional information related to this threat.

• To request incident response resources or technical assistance related to these threats, email CISA at report@cisa.gov. To contact Coast Guard Cyber Command in relation to these threats, email maritimecyber@uscg.mil.
• To report cyber incidents to the Coast Guard pursuant to 33 CFR Section 101.305  contact the USCG NRC (NRC@uscg.mil or 800-424-8802).

Resources

• For more information on Log4Shell, see:
  • CISA’s Apache Log4j Vulnerability Guidance webpage,
  • Joint CSA Mitigating Log4Shell and Other Log4j-Related Vulnerabilities, or
  • CISA’s database of known vulnerable services on the CISA GitHub® page.
• See National Security Agency (NSA) and Australian Signals Directorate (ASD) guidance Block and Defend Web Shell Malware for additional guidance on hardening internet-facing systems.

References

[1] VMware Security Advisory VMSA-2021-0028.13
[2] Fortinet’s blog New Milestones for Deep Panda: Log4Shell and Digitally Signed Fire Chili Rootkits

Appendix A: Indicators of Compromise

See MAR-10382580-1 and MAR-10382254-1 and Table 1 for IOCs. See the list below to download copies of these IOCs: 

• MAR-10382580-1 stix
• MAR-10382254-1 stix

Table 1: Indicators of Compromise

Appendix B: Threat Actor TTPs

See Table 2 for the threat actors’ tactics and techniques identified in this CSA. See the MITRE ATT&CK for Enterprise framework, version 11, for all referenced threat actor tactics and techniques.

Table 2: Tactics and Techniques

Disclaimer

© 2021 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation.

Acknowledgements

CISA and CGCYBER would like to thank VMware and Secureworks for their contributions to this CSA.

Revisions

• June 23, 2022: Initial version

Original release date: June 7, 2022

Summary

Best Practices
• Apply patches as soon as possible
• Disable unnecessary ports and protocols
• Replace end-of-life infrastructure
• Implement a centralized patch management system

This joint Cybersecurity Advisory describes the ways in which People’s Republic of China (PRC) state-sponsored cyber actors continue to exploit publicly known vulnerabilities in order to establish a broad network of compromised infrastructure. These actors use the network to exploit a wide variety of targets worldwide, including public and private sector organizations. The advisory details the targeting and compromise of major telecommunications companies and network service providers and the top vulnerabilities—primarily Common Vulnerabilities and Exposures (CVEs)—associated with network devices routinely exploited by the cyber actors since 2020.

This joint Cybersecurity Advisory was coauthored by the National Security Agency (NSA), the Cybersecurity and Infrastructure Security Agency (CISA), and the Federal Bureau of Investigation (FBI). It builds on previous NSA, CISA, and FBI reporting to inform federal and state, local, tribal, and territorial (SLTT) government; critical infrastructure (CI), including the Defense Industrial Base (DIB); and private sector organizations about notable trends and persistent tactics, techniques, and procedures (TTPs).

Entities can mitigate the vulnerabilities listed in this advisory by applying the available patches to their systems, replacing end-of-life infrastructure, and implementing a centralized patch management program.

NSA, CISA, and the FBI urge U.S. and allied governments, CI, and private industry organizations to apply the recommendations listed in the Mitigations section and Appendix A: Vulnerabilities to increase their defensive posture and reduce the risk of PRC state-sponsored malicious cyber actors affecting their critical networks.

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

Click here for PDF.

Common vulnerabilities exploited by People’s Republic of China state-sponsored cyber actors

PRC state-sponsored cyber actors readily exploit vulnerabilities to compromise unpatched network devices. Network devices, such as Small Office/Home Office (SOHO) routers and Network Attached Storage (NAS) devices, serve as additional access points to route command and control (C2) traffic and act as midpoints to conduct network intrusions on other entities. Over the last few years, a series of high-severity vulnerabilities for network devices provided cyber actors with the ability to regularly exploit and gain access to vulnerable infrastructure devices. In addition, these devices are often overlooked by cyber defenders, who struggle to maintain and keep pace with routine software patching of Internet-facing services and endpoint devices.

Since 2020, PRC state-sponsored cyber actors have conducted widespread campaigns to rapidly exploit publicly identified security vulnerabilities, also known as common vulnerabilities and exposures (CVEs). This technique has allowed the actors to gain access into victim accounts using publicly available exploit code against virtual private network (VPN) services [T1133]  or public facing applications [T1190]—without using their own distinctive or identifying malware—so long as the actors acted before victim organizations updated their systems. 

PRC state-sponsored cyber actors typically conduct their intrusions by accessing compromised servers called hop points from numerous China-based Internet Protocol (IP) addresses resolving to different Chinese Internet service providers (ISPs). The cyber actors typically obtain the use of servers by leasing remote access directly or indirectly from hosting providers. They use these servers to register and access operational email accounts, host C2 domains, and interact with victim networks. Cyber actors use these hop points as an obfuscation technique when interacting with victim networks.

These cyber actors are also consistently evolving and adapting tactics to bypass defenses. NSA, CISA, and the FBI have observed state-sponsored cyber actors monitoring network defenders’ accounts and actions, and then modifying their ongoing campaign as needed to remain undetected. Cyber actors have modified their infrastructure and toolsets immediately following the release of information related to their ongoing campaigns. PRC state-sponsored cyber actors often mix their customized toolset with publicly available tools, especially by leveraging tools that are native to the network environment, to obscure their activity by blending into the noise or normal activity of a network.

NSA, CISA, and the FBI consider the common vulnerabilities and exposures (CVEs) listed in Table 1 to be the network device CVEs most frequently exploited by PRC state-sponsored cyber actors since 2020.

Table 1: Top network device CVEs exploited by PRC state-sponsored cyber actors

Telecommunications and network service provider targeting

PRC state-sponsored cyber actors frequently utilize open-source tools for reconnaissance and vulnerability scanning. The actors have utilized open-source router specific software frameworks, RouterSploit and RouterScan [T1595.002], to identify makes, models, and known vulnerabilities for further investigation and exploitation. The RouterSploit Framework is an open-source exploitation framework dedicated to embedded devices. RouterScan is an open-source tool that easily allows for the scanning of IP addresses for vulnerabilities. These tools enable exploitation of SOHO and other routers manufactured by major industry providers, including Cisco, Fortinet, and MikroTik.

Upon gaining an initial foothold into a telecommunications organization or network service provider, PRC state-sponsored cyber actors have identified critical users and infrastructure including systems critical to maintaining the security of authentication, authorization, and accounting. After identifying a critical Remote Authentication Dial-In User Service (RADIUS) server, the cyber actors gained credentials to access the underlying Structured Query Language (SQL) database [T1078] and utilized SQL commands to dump the credentials [T1555], which contained both cleartext and hashed passwords for user and administrative accounts. 

Having gained credentials from the RADIUS server, PRC state-sponsored cyber actors used those credentials with custom automated scripts to authenticate to a router via Secure Shell (SSH), execute router commands, and save the output [T1119]. These scripts targeted Cisco and Juniper routers and saved the output of the executed commands, including the current configuration of each router. After successfully capturing the command output, these configurations were exfiltrated off network to the actor’s infrastructure [TA0010]. The cyber actors likely used additional scripting to further automate the exploitation of medium to large victim networks, where routers and switches are numerous, to gather massive numbers of router configurations that would be necessary to successfully manipulate traffic within the network.

Armed with valid accounts and credentials from the compromised RADIUS server and the router configurations, the cyber actors returned to the network and used their access and knowledge to successfully authenticate and execute router commands to surreptitiously route [T1599], capture [T1020.001], and exfiltrate traffic out of the network to actor-controlled infrastructure. 

While other manufacturers likely have similar commands, the cyber actors executed the following commands on a Juniper router to perform initial tunnel configuration for eventual exfiltration out of the network:

After establishing the tunnel, the cyber actors configured the local interface on the device and updated the routing table to route traffic to actor-controlled infrastructure.

PRC state-sponsored cyber actors then configured port mirroring to copy all traffic to the local interface, which was subsequently forwarded through the tunnel out of the network to actor-controlled infrastructure. 

Having completed their configuration changes, the cyber actors often modified and/or removed local log files to destroy evidence of their activity to further obfuscate their presence and evade detection.

PRC state-sponsored cyber actors also utilized command line utility programs like PuTTY Link (Plink) to establish SSH tunnels [T1572] between internal hosts and leased virtual private server (VPS) infrastructure. These actors often conducted system network configuration discovery [T1016.001] on these host networks by sending hypertext transfer protocol (HTTP) requests to C2 infrastructure in order to illuminate the external public IP address.

Mitigations

NSA, CISA, and the FBI urge organizations to apply the following recommendations as well as the mitigation and detection recommendations in Appendix A, which are tailored to observed tactics and techniques. While some vulnerabilities have specific additional mitigations below, the following mitigations generally apply:

• Keep systems and products updated and patched as soon as possible after patches are released [D3-SU] . Consider leveraging a centralized patch management system to automate and expedite the process.
• Immediately remove or isolate suspected compromised devices from the network [D3-ITF] [D3-OTF].
• Segment networks to limit or block lateral movement [D3-NI]. 
• Disable unused or unnecessary network services, ports, protocols, and devices [D3-ACH] [D3-ITF] [D3-OTF]. 
• Enforce multifactor authentication (MFA) for all users, without exception [D3-MFA]. 
• Enforce MFA on all VPN connections [D3-MFA]. If MFA is unavailable, enforce password complexity requirements [D3-SPP]. 
• Implement strict password requirements, enforcing password complexity, changing passwords at a defined frequency, and performing regular account reviews to ensure compliance [D3-SPP].
• Perform regular data backup procedures and maintain up-to-date incident response and recovery procedures. 
• Disable external management capabilities and set up an out-of-band management network [D3-NI].
• Isolate Internet-facing services in a network Demilitarized Zone (DMZ) to reduce the exposure of the internal network [D3-NI].
• Enable robust logging of Internet-facing services and monitor the logs for signs of compromise [D3-NTA] [D3-PM].
• Ensure that you have dedicated management systems [D3-PH] and accounts for system administrators. Protect these accounts with strict network policies [D3-UAP].
• Enable robust logging and review of network infrastructure accesses, configuration changes, and critical infrastructure services performing authentication, authorization, and accounting functions [D3-PM]. 
• Upon responding to a confirmed incident within any portion of a network, response teams should scrutinize network infrastructure accesses, evaluate potential lateral movement to network infrastructure and implement corrective actions commensurate with their findings.

Resources

Refer to us-cert.cisa.gov/china, https://www.ic3.gov/Home/IndustryAlerts, and https://www.nsa.gov/cybersecurity-guidance for previous reporting on People’s Republic of China state-sponsored malicious cyber activity.

U.S. government and critical infrastructure organizations, should consider signing up for CISA’s cyber hygiene services, including vulnerability scanning, to help reduce exposure to threats.

U.S. Defense Industrial Base (DIB) organizations, should consider signing up for the NSA Cybersecurity Collaboration Center’s DIB Cybersecurity Service Offerings, including Protective Domain Name System (PDNS) services, vulnerability scanning, and threat intelligence collaboration. For more information on eligibility criteria and how to enroll in these services, email dib_defense@cyber.nsa.gov.

Additional References

• CISA (2022), Weak Security Controls and Practices Routinely Exploited for Initial Access. https://www.cisa.gov/uscert/ncas/alerts/aa22-137a
• CISA (2022) 2021 Top Routinely Exploited Vulnerabilities. https://www.cisa.gov/uscert/ncas/alerts/aa22-117a
• NSA (2021), Selecting and Hardening Remote Access VPN Solutions. https://media.defense.gov/2021/Sep/28/2002863184/-1/-1/0/CSI_SELECTING-HARDENING-REMOTE-ACCESS-VPNS-20210928.PDF 
• NSA (2021), Chinese State-Sponsored Cyber Operations: Observed TTPs. https://media.defense.gov/2021/Jul/19/2002805003/-1/-1/0/CSA_CHINESE_STATE-SPONSORED_CYBER_TTPS.PDF 
• CISA (2021), Exploitation of Pulse Connect Secure Vulnerabilities. https://www.cisa.gov/uscert/ncas/alerts/aa21-110a
• NSA (2020), Chinese State-Sponsored Actors Exploit Publicly Known Vulnerabilities. https://media.defense.gov/2020/Oct/20/2002519884/-1/-1/0/CSA_CHINESE_EXPLOIT_VULNERABILITIES_UOO179811.PDF 
• CISA (2020), Chinese Ministry of State Security-Affiliated Cyber Threat Actor Activity. https://www.cisa.gov/uscert/ncas/alerts/aa20-258a 
• NSA (2020), Performing Out-of-Band Network Management. https://media.defense.gov/2020/Sep/17/2002499616/-1/-1/0/PERFORMING_OUT_OF_BAND_NETWORK_MANAGEMENT20200911.PDF 
• CISA (2020), Critical Vulnerability in Citrix Application Delivery Controller, Gateway, and SD-WAN WANOP. https://www.cisa.gov/uscert/ncas/alerts/aa20-020a
• NSA (2019), Mitigating Recent VPN Vulnerabilities. https://media.defense.gov/2019/Oct/07/2002191601/-1/-1/0/Mitigating%20Recent%20VPN%20Vulnerabilities%20-%20Copy.pdf 
• NSA (2019), Update and Upgrade Software Immediately. https://media.defense.gov/2019/Sep/09/2002180319/-1/-1/0/Update%20and%20Upgrade%20Software%20Immediately.docx%20-%20Copy.pdf 

Contact Information 

To report incidents and anomalous activity or to request incident response resources or technical assistance related to these threats, contact CISA at report@cisa.gov. To report computer intrusion or cybercrime activity related to information found in this advisory, contact your local FBI field office at www.fbi.gov/contact-us/field, or the FBI’s 24/7 Cyber Watch at 855-292-3937 or by email at CyWatch@fbi.gov. For NSA client requirements or general cybersecurity inquiries, contact Cybersecurity_Requests@nsa.gov. 

Media Inquiries / Press Desk: 

• NSA Media Relations, 443-634-0721, MediaRelations@nsa.gov  
• CISA Media Relations, 703-235-2010, CISAMedia@cisa.dhs.gov 
• FBI National Press Office, 202-324-3691, npo@fbi.gov 

Disclaimer of endorsement

The information and opinions contained in this document are provided “as is” and without any warranties or guarantees. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not constitute or imply its endorsement, recommendation, or favoring by the United States Government, and this guidance shall not be used for advertising or product endorsement purposes.

Purpose

This advisory was developed by NSA, CISA, and the FBI in furtherance of their respective cybersecurity missions, including their responsibilities to develop and issue cybersecurity specifications and mitigations. This information may be shared broadly to reach all appropriate stakeholders. 

Appendix A: Vulnerabilities

Table 2: Information on Cisco CVE-2018-0171

Table 3: Information on Cisco CVE-2019-15271

Table 4: Information on Cisco CVE-2019-1652

Table 5: Information on Citrix CVE-2019-19781

Table 6: Information on DrayTek CVE-2020-8515

Table 7: Information on D-Link CVE-2019-16920

Table 8: Information on Fortinet CVE-2018-13382

Table 9: Information on Mikrotik CVE-2018-14847

Table 10: Information on Netgear CVE-2017-6862

Table 11: Information on Pulse CVE-2019-11510

Table 12: Information on Pulse CVE-2021-22893

Table 13: Information on QNAP CVE-2019-7192

Table 14: Information on QNAP CVE- 2019-7193

Table 15: Information on QNAP CVE-2019-7194

Table 16: Information on QNAP CVE-2019-7195

Table 17: Information on Zyxel CVE-2020-29583

Revisions

• Initial Version: June 7, 2022

Original release date: June 1, 2022

Summary

Actions to take today to mitigate cyber threats from ransomware:
• Prioritize patching known exploited vulnerabilities.
• Train users to recognize and report phishing attempts.
• Enforce multifactor authentication.

The Federal Bureau of Investigation (FBI), the Cybersecurity and Infrastructure Security Agency (CISA), the Department of the Treasury (Treasury), and the Financial Crimes Enforcement Network (FinCEN) are releasing this joint Cybersecurity Advisory (CSA) to provide information on the Karakurt data extortion group, also known as the Karakurt Team and Karakurt Lair. Karakurt actors have employed a variety of tactics, techniques, and procedures (TTPs), creating significant challenges for defense and mitigation. Karakurt victims have not reported encryption of compromised machines or files; rather, Karakurt actors have claimed to steal data and threatened to auction it off or release it to the public unless they receive payment of the demanded ransom. Known ransom demands have ranged from $25,000 to $13,000,000 in Bitcoin, with payment deadlines typically set to expire within a week of first contact with the victim.

Karakurt actors have typically provided screenshots or copies of stolen file directories as proof of stolen data. Karakurt actors have contacted victims’ employees, business partners, and clients [T1591.002] with harassing emails and phone calls to pressure the victims to cooperate. The emails have contained examples of stolen data, such as social security numbers, payment accounts, private company emails, and sensitive business data belonging to employees or clients. Upon payment of ransoms, Karakurt actors have provided some form of proof of deletion of files and, occasionally, a brief statement explaining how the initial intrusion occurred.

Prior to January 5, 2022, Karakurt operated a leaks and auction website found at https://karakurt[.]group. The domain and IP address originally hosting the website went offline in the spring 2022. The website is no longer accessible on the open internet, but has been reported to be located elsewhere in the deep web and on the dark web. As of May 2022, the website contained several terabytes of data purported to belong to victims across North America and Europe, along with several “press releases” naming victims who had not paid or cooperated, and instructions for participating in victim data “auctions.”

Download the PDF version of this report (pdf, 569kb).

Technical Details

Initial Intrusion

Karakurt does not appear to target any specific sectors, industries, or types of victims. During reconnaissance [TA0043], Karakurt actors appear to obtain access to victim devices primarily:

• By purchasing stolen login credentials [T1589.001] [T1589.002]; 
• Via cooperating partners in the cybercrime community, who provide Karakurt access to already compromised victims; or 
• Through buying access to already compromised victims via third-party intrusion broker networks [T1589.001].
  • Note: Intrusion brokers, or intrusion broker networks, are malicious individual cyber actors or groups of actors who use a variety of tools and skills to obtain initial access to—and often create marketable persistence within—protected computer systems. Intrusion brokers then sell access to these compromised computer systems to other cybercriminal actors, such as those engaged in ransomware, business email compromise, corporate and government espionage, etc. 

Common intrusion vulnerabilities exploited for initial access [TA001] in Karakurt events include the following:

• Outdated SonicWall SSL VPN appliances [T1133] are vulnerable to multiple recent CVEs 
• Log4j “Log4Shell” Apache Logging Services vulnerability (CVE-2021-44228) [T1190]
• Phishing and spearphishing [T1566]
• Malicious macros within email attachments [T1566.001]
• Stolen virtual private network (VPN) or Remote Desktop Protocol (RDP) credentials [T1078]
• Outdated Fortinet FortiGate SSL VPN appliances [T1133]/firewall appliances [T1190] are vulnerable to multiple recent CVEs
• Outdated and/or unserviceable Microsoft Windows Server instances

Network Reconnaissance, Enumeration, Persistence, and Exfiltration

Upon developing or obtaining access to a compromised system, Karakurt actors deploy Cobalt Strike beacons to enumerate a network [T1083], install Mimikatz to pull plain-text credentials [T1078], use AnyDesk to obtain persistent remote control [T1219], and utilize additional situation-dependent tools to elevate privileges and move laterally within a network.

Karakurt actors then compress (typically with 7zip) and exfiltrate large sums of data—and, in many cases, entire network-connected shared drives in volumes exceeding 1 terabyte (TB)—using open source applications and File Transfer Protocol (FTP) services [T1048], such as Filezilla, and cloud storage services including rclone and Mega.nz [T1567.002]. 

Extortion

Following the exfiltration of data, Karakurt actors present the victim with ransom notes by way of “readme.txt” files, via emails sent to victim employees over the compromised email networks, and emails sent to victim employees from external email accounts. The ransom notes reveal the victim has been hacked by the “Karakurt Team” and threaten public release or auction of the stolen data. The instructions include a link to a TOR URL with an access code. Visiting the URL and inputting the access code open a chat application over which victims can negotiate with Karakurt actors to have their data deleted. 

Karakurt victims have reported extensive harassment campaigns by Karakurt actors in which employees, business partners, and clients receive numerous emails and phone calls warning the recipients to encourage the victims to negotiate with the actors to prevent the dissemination of victim data. These communications often included samples of stolen data—primarily personally identifiable information (PII), such as employment records, health records, and financial business records.

Victims who negotiate with Karakurt actors receive a “proof of life,” such as screenshots showing file trees of allegedly stolen data or, in some cases, actual copies of stolen files. Upon reaching an agreement on the price of the stolen data with the victims, Karakurt actors provided a Bitcoin address—usually a new, previously unused address—to which ransom payments could be made. Upon receiving the ransom, Karakurt actors provide some form of alleged proof of deletion of the stolen files, such as a screen recording of the files being deleted, a deletion log, or credentials for a victim to log into a storage server and delete the files themselves.

Although Karakurt’s primary extortion leverage is a promise to delete stolen data and keep the incident confidential, some victims reported Karakurt actors did not maintain the confidentiality of victim information after a ransom was paid. Note: the U.S. government strongly discourages the payment of any ransom to Karakurt threat actors, or any cyber criminals promising to delete stolen files in exchange for payments.

In some cases, Karakurt actors have conducted extortion against victims previously attacked by other ransomware variants. In such cases, Karakurt actors likely purchased or otherwise obtained previously stolen data. Karakurt actors have also targeted victims at the same time these victims were under attack by other ransomware actors. In such cases, victims received ransom notes from multiple ransomware variants simultaneously, suggesting Karakurt actors purchased access to a compromised system that was also sold to another ransomware actor.

Karakurt actors have also exaggerated the degree to which a victim had been compromised and the value of data stolen. For example, in some instances, Karakurt actors claimed to steal volumes of data far beyond the storage capacity of compromised systems or claimed to steal data that did not belong to the victim.
 

Indicators of Compromise 

.

Mitre Att&ck Techniques

Karakurt actors use the ATT&CK techniques listed in table 1.
 

Table 1: Karakurt actors ATT&CK techniques for enterprise

Mitigations

• 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, the cloud).
• Implement network segmentation and maintain offline backups of data to ensure limited interruption to the organization.
• Regularly back up data and password protect backup copies offline. Ensure copies of critical data are not accessible for modification or deletion from the system where the data resides.
• Install and regularly update antivirus software on all hosts and enable real time detection.
• Install updates/patch operating systems, software, and firmware as soon as updates/patches are released.
• Review domain controllers, servers, workstations, and active directories for new or unrecognized accounts. 
• Audit user accounts with administrative privileges and configure access controls with least privilege in mind. Do not give all users administrative privileges.
• Disable unused ports.
• Consider adding an email banner to emails received from outside your organization.
• Disable hyperlinks in received emails.
• Enforce multi-factor authentication. 
• Use National Institute for Standards and Technology (NIST) standards for developing and managing password policies.
  • Use longer passwords consisting of at least 8 characters and no more than 64 characters in length;
  • Store passwords in hashed format using industry-recognized password managers;
  • Add password user “salts” to shared login credentials;
  • Avoid reusing passwords;
  • Implement multiple failed login attempt account lockouts;
  • 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.
• Only use secure networks and avoid using public Wi-Fi networks. Consider installing and using a VPN.
• Focus on cyber security awareness and training. Regularly provide users with training on information security principles and techniques as well as overall emerging cybersecurity risks and vulnerabilities (i.e., ransomware and phishing scams).

Resources

• For additional resources related to the prevention and mitigation of ransomware, visit Stopransomware.gov as well as the CISA-Multi-State Information Sharing and Analysis Center (MS-ISAC) Joint Ransomware Guide and NIST’s Data Integrity: Detecting and Responding to Ransomware and Other Destructive Events. Stopransomware.gov is the U.S. government’s one-stop location for resources to tackle ransomware more effectively.
• CISA’s Ransomware Readiness Assessment is a no-cost self-assessment based on a tiered set of practices to help organizations better assess how well they are equipped to defend and recover from a ransomware incident. 
• CISA offers a range of no-cost cyber hygiene services to help critical infrastructure organizations assess, identify, and reduce their exposure to threats, including ransomware. 
• Financial Institutions must also ensure compliance with any applicable Bank Secrecy Act requirements, including suspicious activity reporting obligations. Indicators of Compromise, such as suspicious email addresses, file names, hashes, domains, and IP addresses, can be provided under Item 44 of the Suspicious Activity Report (SAR) form. For more information on mandatory and voluntary reporting of cyber events via suspicious activity reports (SARs), see FinCEN Advisory FIN-2016-A005, Advisory to Financial Institutions on Cyber-Events and Cyber-Enabled Crime, October 25, 2016, and FinCEN Advisory FIN-2021-A004, Advisory on Ransomware and the Use of the Financial System to Facilitate Ransom Payments, November 8, 2021, which updates FinCEN Advisory FIN-2020-A006.
• 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. 

Revisions

• Initial Version: June 01, 2022