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The Federal Bureau of Investigation (FBI) and the Cybersecurity and Infrastructure Security Agency (CISA) have released a this joint CSA to disseminate known ransomware IOCs and TTPs associated with the Snatch ransomware variant.  

Since mid-2021, Snatch threat actors have consistently evolved their tactics to take advantage of current trends in the cybercriminal space and leveraged successes of other ransomware variants’ operations.  Snatch threat actors have targeted a wide range of critical infrastructure sectors including the Defense Industrial Base (DIB), Food and Agriculture, and Information Technology sectors.  Snatch threat actors conduct ransomware operations involving data exfiltration and double extortion.  After data exfiltration often involving direct communications with victims demanding ransom, Snatch threat actors may threaten victims with double extortion, where the victims’ data will be posted on Snatch’s extortion blog if the ransom goes unpaid.[1]

TECHNICAL DETAILS - Note: This CISA advisory uses the MITRE ATT&CK for Enterprise framework, version 13. 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.

First appearing in 2018, Snatch operates a ransomware-as-a-service (RaaS) model and claimed their first US-based victim in 2019.  Originally, the group was referred to as Team Truniger, based on the nickname of a key group member, Truniger, who previously operated as a GandCrab affiliate.  Snatch threat actors use a customized ransomware variant notable for rebooting devices into Safe Mode [T1562.009], enabling the ransomware to circumvent detection by antivirus or endpoint protection, and then encrypting files when few services are running.

Snatch threat actors have been observed purchasing previously stolen data from other ransomware variants to further exploit victims into paying a ransom to avoid having their data released on Snatch’s extortion blog.  Since November 2021, an extortion site operating under the name Snatch served as a clearinghouse for data exfiltrated or stolen from victim companies on Clearnet and TOR hosted by a bulletproof hosting service.  In August 2023, individuals claiming to be associated with the blog gave a media interview claiming the blog was not associated with Snatch ransomware and “none of our targets has been attacked by Ransomware Snatch…”, despite multiple confirmed Snatch victims’ data appearing on the blog alongside victims associated with other ransomware groups, notably Nokoyawa and Conti.

Initial Access and Persistence - Snatch threat actors employ several different methods to gain access to and maintain persistence on a victim’s network. Snatch affiliates primarily rely on exploiting weaknesses in Remote Desktop Protocol (RDP) [T1133] for brute-forcing and gaining administrator credentials to victims’ networks [T1110.001].  In some instances, Snatch affiliates have sought out compromised credentials from criminal forums/marketplaces [T1078].

Snatch threat actors gain persistence on a victim’s network by compromising an administrator account [T1078.002] and establishing connections over port 443 [T1071.001] to a command and control (C2) server located on a Russian bulletproof hosting service [T1583.003].  Per IP traffic from event logs provided by recent victims, Snatch threat actors initiated RDP connections from a Russian bulletproof hosting service and through other virtual private network (VPN) services [T1133].

Data Discovery and Lateral Movement - Snatch threat actors were observed using different TTPs to discover data, move laterally, and search for data to exfiltrate.  Snatch threat actors use sc.exe to configure, query, stop, start, delete, and add system services using the Windows Command line.  In addition to sc.exe, Snatch threat actors also use tools such as Metasploit and Cobalt Strike [S0154].

Prior to deploying the ransomware, Snatch threat actors were observed spending up to three months on a victim’s system.  Within this timeframe, Snatch threat actors exploited the victim’s network [T1590], moving laterally across the victim’s network with RDP [T1021.001] for the largest possible deployment of ransomware and searching for files and folders [T1005] for data exfiltration [TA0010] followed by file encryption [T1486].

Defense Evasion and Execution - During the early stages of ransomware deployment, Snatch threat actors attempt to disable antivirus software and run an executable as a file named safe.exe or some variation thereof.  In recent victims, the ransomware executable’s name consisted of a string of hexadecimal characters which match the SHA-256 hash of the file in an effort to defeat rule-based detection.  Upon initiation, the Snatch ransomware payload queries and modifies registry keys, uses various native Windows tools to enumerate the system, finds processes and creates benign processes to execute Windows batch (.bat) files.  In some instances, the program attempts to remove all the volume shadow copies from a system.  After the execution of the batch files, the executable removes the batch files from the victim’s filesystem.

The Snatch ransomware executable appends a series of hexadecimal characters to each file and folder name it encrypts—unique to each infection—and leaves behind a text file titled HOW TO RESTORE YOUR FILES.TXT in each folder.  Snatch threat actors communicate with their victims through email and the Tox communication platform based on identifiers left in ransom notes or through their extortion blog.  Since November 2021, some victims reported receiving a spoofed call from an unknown female who claimed association with Snatch and directed them to the group’s extortion site.  In some instances, Snatch victims had a different ransomware variant deployed on their systems, but received a ransom note from Snatch threat actors.  As a result, the victims’ data is posted on the ransomware blog involving the different ransomware variant and on the Snatch threat actors’ extortion blog.

Indicators of Compromise (IOCs) - The Snatch IOCs detailed in this section were obtained through FBI investigations from September 2022 through June 2023.

Email Domains and Addresses - Since 2019, Snatch threat actors have used numerous email addresses to email victims.  Email addresses used by Snatch threat actors are random but usually originate from one of the following domains listed in Tables 1 and 2:

Table 2 shows a list of legitimate email domains offering encrypted email services that have been used by Snatch threat actors.  These email domains are all publicly available and legal.  The use of these email domains by a threat actor should not be attributed to the email domains, absent specific articulable facts tending to show they are used at the direction or under the control of a threat actor.

The email addresses listed in Table 3 were reported by recent victims.

MITRE ATT&CK TACTICS AND TECHNIQUES

See Tables 4-16 for all referenced threat actor tactics and techniques in this advisory.

MITIGATIONS

The FBI and CISA recommend organizations implement the mitigations below to improve your organization’s cybersecurity posture on the basis of the Snatch threat actor’s 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.

Reduce threat of malicious actors using remote access tools by:

• Auditing remote access toolson your network to identify currently used and/or authorized software.
• Reviewing logs for execution of remote access softwareto detect abnormal use of programs running as a portable executable [CPG 2.T].
• Using security softwareto detect instances of remote access software being loaded only in memory.
• Requiring authorized remote access solutionsto be used only from within your network over approved remote access solutions, such as virtual private networks (VPNs) or virtual desktop interfaces (VDIs).
• Blocking both inbound and outbound connectionson common remote access software ports and protocols at the network perimeter.
• 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 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 scriptingactivities and permissions [CPG 2.N].
• Review domain controllers, servers, workstations, and active directoriesfor new and/or unrecognized accounts [CPG 4.C].
• Audit user accounts with administrative privilegesand configure access controls according to the principle of least privilege (PoLP) [CPG 2.E].
• Reduce the threat of credential compromisevia the following:
• Place domain admin accounts in the protected users’ groupto prevent caching of password hashes locally.
• Refrain from storing plaintext credentials in scripts.
• Implement time-based access for accountsset 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 planto 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).
• 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 accountswith 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 eight 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].
• 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 networksto 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 softwareon all hosts.
• Disable unusedports and protocols [CPG 2.V].
• Consider adding an email banner to emailsreceived from outside your organization [CPG 2.M].
• Disable hyperlinksin 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, 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.  FBI and CISA recommend testing your existing security controls inventory to assess how they perform against the ATT&CK techniques described in this advisory.

To get started:

• Select an ATT&CK technique described in this advisory (see Tables 4-16).
• Align your security technologies against the technique.
• Test your technologies against the technique.
• Analyze your detection and prevention technologies’ performance.
• Repeat the process for all security technologies to obtain a set of comprehensive performance data.
• 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.

 RESOURCES:

• govis 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 Servicesand Ransomware Readiness Assessment.

This article is presented at no charge for educational and informational purposes only.

Red Sky Alliance is a Cyber Threat Analysis and Intelligence Service organization and has reported extensively on AI technology.  For questions, comments or assistance, please contact the office directly at 1-844-492-7225, or feedback@redskyalliance.com    

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[1] https://www.cisa.gov/news-events/cybersecurity-advisories/aa23-263a