Table of Contents
The Cuba ransomware group, despite its name having no known connection to the Republic of Cuba, has emerged as a significant and evolving cyber threat since its initial appearance in 2019. Gaining notoriety in late 2021 following FBI advisories, this group has demonstrated increasing sophistication and impact, particularly targeting critical infrastructure sectors across the globe. Characterized by its double extortion tactics—encrypting victim data while also threatening to leak exfiltrated sensitive information—Cuba ransomware poses a substantial financial and operational risk. As a security advisor, understanding the specific Tactics, Techniques, and Procedures (TTPs) employed by this group is crucial for security professionals aiming to bolster defenses and effectively combat this persistent threat. This article provides a technical deep dive into the Cuba ransomware group, covering its origins, operational methods, target profile, notable campaigns, and essential defense strategies.
Origins & Evolution
The Cuba ransomware group was first observed in 2019 but began attracting significant attention from cybersecurity researchers and law enforcement agencies like the FBI and CISA around November 2021. This increased focus was driven by a surge in attacks targeting numerous organizations, particularly within the United States.
Origin and Affiliation: Despite the group's name and the nationalistic styling sometimes seen on its leak site, there is no evidence linking it to the Republic of Cuba. Analysis of the ransomware code and associated tools, along with linguistic clues found in communications and leak sites, strongly suggests the involvement of Russian-speaking actors. Notably, the ransomware often includes checks to terminate execution if it detects Russian language settings or keyboard layouts on the compromised system.
Evolution: Since its emergence, the Cuba ransomware group has continuously evolved its TTPs. Initially leveraging common tactics, the group significantly updated its operations starting around Spring 2022. This evolution includes:
New Exploits: Incorporating exploits for newly disclosed vulnerabilities, such as CVE-2022-24521 (Windows Common Log File System Driver) for privilege escalation and, more recently in 2023, CVE-2023-27532 (Veeam Backup & Replication vulnerability) to access credentials and potentially hinder recovery efforts.
Updated Tooling: Refining custom malware like the BUGHATCH downloader/backdoor and the BURNTCIGAR anti-malware tool, often making subtle modifications (e.g., adding hashing functionality) to evade detection.
Potential Associations: Research suggests potential links between the Cuba ransomware operators and other threat entities. Palo Alto Networks' Unit 42 linked the group to an actor tracked as "Tropical Scorpius," known for deploying the RomCom RAT. Furthermore, there have been indications of a relationship with the Industrial Spy data extortion marketplace, which was reportedly used as a leak site for data stolen by the Cuba group in 2022.
This constant adaptation highlights the group's commitment to maintaining operational effectiveness and circumventing security measures, making continuous monitoring and threat intelligence crucial for defenders.
Tactics & Techniques
The Cuba ransomware group employs a multifaceted approach, combining custom tools, commodity malware, legitimate system utilities (Living-off-the-Land Binaries or LOLBins), and exploits to achieve its objectives. Their mode of operandi typically follows these stages:
Initial Access: Cuba operators gain entry into target networks through various methods:
Exploitation of Vulnerabilities: Targeting known vulnerabilities in public-facing applications, notably Microsoft Exchange servers (ProxyShell, ProxyLogon, CVE-2022-41080) and, more recently, Veeam Backup & Replication (CVE-2023-27532).
Phishing: Utilizing malicious emails, sometimes highly targeted (spear-phishing), as seen in campaigns against Ukrainian government entities.
Compromised Credentials: Leveraging stolen or weak credentials, potentially acquired through other breaches or initial access brokers.
Remote Desktop Protocol (RDP): Using legitimate RDP tools with compromised credentials for initial access and lateral movement.
Malware Loaders: Historically associated with the Hancitor malware loader (also known as Chanitor) to deliver the ransomware payload along with other malware like Remote Access Trojans (RATs).
Execution and Persistence: Once inside, the group uses various techniques:
Command and Scripting: Heavy reliance on PowerShell for downloading payloads, executing commands, and interacting with Cobalt Strike beacons. Windows Command Shell (
cmd.exe) is also used.Custom Malware Deployment: Utilizing the BUGHATCH downloader to fetch and execute further payloads, including Cobalt Strike or Metasploit frameworks. BUGHATCH often operates in memory to reduce its footprint.
Persistence Mechanisms: Establishing persistence using Scheduled Tasks (T1053.005) and modifying Registry Run Keys or Startup Folders (T1547.001).
Privilege Escalation: To gain higher levels of access, Cuba employs:
Exploitation: Using exploits for vulnerabilities like ZeroLogon (CVE-2020-1472) to gain Domain Admin rights and CVE-2022-24521 (Windows CLFS driver) to steal system tokens.
Credential Dumping: Utilizing tools like Mimikatz to dump credentials, particularly from the LSASS process memory (T1003.001).
Kerberoasting: Targeting Active Directory service accounts to crack their Kerberos tickets offline (T1558.003), often using tools like KerberCache.
Defense Evasion: To avoid detection and removal, the group uses:
Antivirus Killer: Deploying the BURNTCIGAR tool, which uses a Bring Your Own Vulnerable Driver (BYOVD) technique. It leverages legitimate but vulnerable drivers (e.g.,
ApcHelper.syssigned with a leaked NVIDIA certificate,aswArPot.sysfrom Avast,KApcHelper_x64.sys,procexp152.sys) to terminate security product processes (T1562.001).Masquerading: Renaming tools or using legitimate system process names to hide malicious activity.
Encrypted Payloads/C2: Using encryption to obscure malware components and communication channels.
Lateral Movement: To spread across the network, Cuba utilizes:
Remote Services: Employing RDP (T1021.001) and SMB/Windows Admin Shares (T1021.002) with stolen credentials.
Legitimate Tools: Using tools like PsExec and PowerShell for remote code execution.
Frameworks: Leveraging Cobalt Strike and Metasploit for lateral movement capabilities.
Network Discovery: Using tools like
net.exe,nltest,ping.exe, and custom host enumeration tools (Wedgecut) to map the network (T1018, T1135).
Command and Control (C2): Communication with attacker infrastructure is maintained via:
Custom Backdoors: BUGHATCH establishes connections to C2 servers to receive commands and download additional tools.
RATs: Potential use of RomCom RAT for C2.
Penetration Testing Frameworks: Cobalt Strike beacons provide robust C2 channels, often over HTTP/HTTPS.
TOR Network: Utilized for hosting the data leak site.
Impact: The final stage involves achieving the group's primary objective:
Data Exfiltration: Sensitive data (financial documents, PII, source code, etc.) is exfiltrated before encryption to be used in the double extortion scheme (T1041).
Data Encryption: Files are encrypted using strong algorithms, and the
.cubaextension is appended. Critical system files are usually excluded to keep the system bootable for ransom payment.Ransom Note: A ransom note is dropped, directing victims to a TOR-based site for payment instructions, typically demanding large sums in Bitcoin.
MITRE ATT&CK TTPs:
|
Tactic
|
Technique ID
|
Technique Name
|
|---|---|---|
|
Reconnaissance
|
T1592
|
Gather Victim Host Information
|
|
Resource Development
|
T1587.001
|
Develop Capabilities: Malware
|
|
Initial Access
|
T1133
|
External Remote Services
|
|
Initial Access
|
T1190
|
Exploit Public-Facing Application
|
|
Initial Access
|
T1566
|
Phishing
|
|
Initial Access
|
T1078
|
Valid Accounts
|
|
Execution
|
T1059.001
|
Command and Scripting Interpreter: PowerShell
|
|
Execution
|
T1059.003
|
Command and Scripting Interpreter: Windows Command Shell
|
|
Execution
|
T1204.002
|
User Execution: Malicious File
|
|
Persistence
|
T1053.005
|
Scheduled Task/Job: Scheduled Task
|
|
Persistence
|
T1547.001
|
Boot or Logon AutoStart Execution: Registry Run Keys / Startup Folder
|
|
Privilege Escalation
|
T1068
|
Exploitation for Privilege Escalation
|
|
Privilege Escalation
|
T1558.003
|
Steal or Forge Kerberos Tickets: Kerberoasting
|
|
Defense Evasion
|
T1562.001
|
Impair Defenses: Disable or Modify Tools
|
|
Defense Evasion
|
T1036.004
|
Masquerading: Masquerade Task or Service
|
|
Credential Access
|
T1003.001
|
OS Credential Dumping: LSASS Memory
|
|
Discovery
|
T1018
|
Remote System Discovery
|
|
Discovery
|
T1082
|
System Information Discovery
|
|
Discovery
|
T1016
|
System Network Configuration Discovery
|
|
Discovery
|
T1033
|
System Owner/User Discovery
|
|
Discovery
|
T1083
|
File and Directory Discovery
|
|
Discovery
|
T1135
|
Network Share Discovery
|
|
Lateral Movement
|
T1021.001
|
Remote Services: Remote Desktop Protocol
|
|
Lateral Movement
|
T1021.002
|
Remote Services: SMB/Windows Admin Shares
|
|
Lateral Movement
|
T1072
|
Software Deployment Tools (e.g., PsExec)
|
|
Command and Control
|
T1071.001
|
Application Layer Protocol: Web Protocols (HTTP/HTTPS)
|
|
Command and Control
|
T1090
|
Proxy (Used by tools like Cobalt Strike)
|
|
Exfiltration
|
T1041
|
Exfiltration Over C2 Channel
|
|
Impact
|
T1486
|
Data Encrypted for Impact
|
|
Impact
|
T1490
|
Inhibit System Recovery (e.g., deleting shadow copies)
|
Targets or Victimology
Motivations: The primary driver behind the Cuba ransomware group's activities is financial gain. This is evident from their ransomware model, substantial ransom demands (reportedly reaching over $145 million in demands by late 2022), and the double extortion tactic designed to maximize pressure on victims to pay. They also use cryptocurrency to get the ransom without revealing their identity.
Target Industries: Cuba operators have demonstrated a clear focus on critical infrastructure sectors. Based on reports from CISA, FBI, and various security vendors, the most frequently targeted industries include:
Financial Services
Government Facilities (at national and local levels)
Healthcare and Public Health
Critical Manufacturing
Information Technology
Transportation and Logistics
Energy
Entertainment/Media (e.g., The Philadelphia Inquirer)
Targeting these sectors maximizes potential disruption and increases the likelihood of ransom payment due to the critical nature of their operations.
Target Regions: While having a global reach, the group predominantly targets organizations in Western, democratic, and Anglophone countries. Key regions include:
North America (especially the United States)
Europe
Latin America
Oceania (Australia)
Asia
Potential Impact: Attacks by the Cuba ransomware group can have severe consequences beyond financial loss from ransom payments:
Operational Disruption: Encryption of critical systems can halt business operations for extended periods.
Data Breach: Exfiltration of sensitive data (customer PII, employee records, intellectual property, financial data) leads to regulatory fines, reputational damage, and potential follow-on attacks.
Recovery Costs: Significant expenses are incurred for incident response, system restoration, and security improvements post-attack.
Supply Chain Effects: Attacks on IT providers or critical suppliers (like the reported attack on a payment processor) can have cascading effects on their customers. One potential effect might be software and data integrity failures.
Attack Campaigns
The Cuba ransomware group has been linked to numerous high-impact campaigns since gaining prominence. Some notable examples include:
FBI/CISA Reports (Dec 2021 & Dec 2022): These advisories highlighted the group's targeting of at least 49 entities in 2021, doubling to over 100 by late 2022, across five US critical infrastructure sectors. The reports detailed their evolving TTPs and significant financial demands/receipts ($145M+ demanded, $60M+ received by late 2022).
Montenegro Government Attack (Aug/Sep 2022): Cuba ransomware was implicated in a major cyberattack targeting government infrastructure in Montenegro, affecting numerous workstations across multiple institutions and leading to the exfiltration of sensitive data.
Targeting Ukrainian Entities (Oct 2022): CERT-UA warned of Cuba utilizing phishing emails disguised as official Ukrainian military communications to deliver the RomCom RAT, demonstrating targeted attacks aligned with geopolitical contexts.
Chilean Government Servers (2022): Reports indicated Cuba targeted Microsoft and VMware ESXi servers within Chilean government networks, encrypting files and leaving ransom notes.
Exploitation of Microsoft Exchange Vulnerabilities (Early 2023): The group was observed exploiting Exchange vulnerabilities like CVE-2022-41080 (related to ProxyNotShell) for initial access, a tactic also used by other ransomware groups like Play.
Philadelphia Inquirer Attack (May 2023): Cuba claimed responsibility for a cyberattack against the major US newspaper, causing significant disruption to its printing and distribution operations.
US Critical Infrastructure & LATAM IT Integrator (June 2023): BlackBerry detailed a campaign where Cuba targeted these entities, notably employing an exploit for the Veeam Backup & Replication vulnerability (CVE-2023-27532) for the first time, alongside their established tools like BUGHATCH and BURNTCIGAR. They are trying to exfiltrate credentials using credential theft.
These campaigns illustrate the group's consistent activity, evolving capabilities, and broad targeting strategy focused on impactful disruption and extortion.
Defenses
Defending against a sophisticated and adaptable threat like the Cuba ransomware group requires a multi-layered security strategy focusing on prevention, detection, and response readiness. Based on the group's known TTPs, the following defense strategies are recommended:
Prevention:
Patch Management: Maintain a rigorous patch management program. Prioritize patching for known exploited vulnerabilities frequently used by Cuba, including those in Microsoft Exchange (ProxyShell, ProxyLogon, CVE-2022-41080), NetLogon (Zerologon/CVE-2020-1472), Windows CLFS (CVE-2022-24521), and Veeam Backup & Replication (CVE-2023-27532).
Strong Authentication: Implement Multi-Factor Authentication (MFA) for all remote access (VPNs, RDP), privileged accounts, and critical applications. Enforce strong, unique password policies compliant with NIST guidelines.
Email Security: Deploy advanced email authentication solutions to filter phishing attempts and malicious attachments. Train users to identify and report suspicious emails. Consider disabling hyperlinks in emails from external sources.
Secure Remote Access: Harden RDP configurations (e.g., use Network Level Authentication, limit access via firewalls) or disable it if not essential. Secure VPN gateways and monitor access logs.
Least Privilege: Implement the principle of least privilege for all accounts and services. Restrict administrative privileges and use time-based access (Just-In-Time) for administrative tasks.
Disable Unnecessary Shares/Services: Remove unnecessary access to administrative shares (e.g., C$, ADMIN$). If required, restrict permissions and monitor usage closely. Disable unused ports and services.
Detection:
Endpoint Detection and Response (EDR): Deploy EDR solutions capable of detecting malicious PowerShell execution, credential dumping attempts (Mimikatz, LSASS access), process injection, and the specific behaviors of tools like BUGHATCH and BURNTCIGAR. Ensure EDR can detect/block the use of known vulnerable drivers.
Network Monitoring: Monitor network traffic for C2 communications (Cobalt Strike, Metasploit, RomCom RAT), unusual data exfiltration patterns, lateral movement attempts (RDP, PsExec, SMB), and connections to known malicious IP addresses or TOR nodes. Implement network segmentation to limit blast radius.
Log Analysis: Collect and analyze logs from endpoints, servers, Active Directory, firewalls, and VPNs. Look for signs of anomalous logins, privilege escalation attempts, suspicious script execution, and use of tools like PsExec or PowerShell remoting. For better log analysis you can use Splunk.
Threat Intelligence: Utilize threat intelligence feeds to stay updated on Cuba's latest TTPs, IOCs (IP addresses, domains, file hashes, certificate hashes), and exploited vulnerabilities. Block known IOCs proactively.
Response and Resilience:
Data Backup and Recovery: Maintain regular, tested backups of critical data. Ensure backups are stored offline or in immutable storage (air-gapped or cloud-based immutable buckets) and are protected from encryption or deletion by ransomware. Regularly test restoration procedures.
Incident Response Plan: Develop and regularly exercise an incident response plan specifically tailored to handle ransomware attacks, including steps for containment, eradication, recovery, and communication.
Network Segmentation: Segment networks to prevent ransomware from spreading laterally between different parts of the organization. Isolate critical systems and backup infrastructure.
By implementing these comprehensive strategies, organizations can significantly reduce their risk of compromise by the Cuba ransomware group and enhance their ability to detect and respond effectively if an attack occurs. You can consider SOAR for automation and orchestration in cybersecurity .
Conclusion
The Cuba ransomware group remains a potent and active threat in the cybercrime landscape, distinguished by its financial motivations, targeting of critical infrastructure, and continually evolving TTPs. Believed to be operated by Russian-speaking actors, the group leverages a combination of known vulnerability exploits, custom malware like BUGHATCH and BURNTCIGAR, and commodity tools including Cobalt Strike and Metasploit. Their double extortion model amplifies the potential damage, making prevention and rapid detection paramount. Security professionals must remain vigilant, employing robust defense-in-depth strategies that include timely patching, strong authentication, network segmentation, advanced endpoint protection, comprehensive monitoring, and well-rehearsed incident response plans to effectively counter this persistent adversary.
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Arun KL
Arun KL is a cybersecurity professional with 15+ years of experience in IT infrastructure, cloud security, vulnerability management, Penetration Testing, security operations, and incident response. He is adept at designing and implementing robust security solutions to safeguard systems and data. Arun holds multiple industry certifications including CCNA, CCNA Security, RHCE, CEH, and AWS Security.
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