⚠️ Overview

Cuba is a ransomware family first observed in December 2019, attributed to the threat group tracked as FIN12 (also linked to UNC1878) by Mandiant and others, and later associated with the Cuba Ransomware Gang. It operates as a ransomware-as-a-service model, primarily targeting large enterprises in critical infrastructure sectors for double extortion—encrypting files and exfiltrating data.

🔧 Technical Capabilities

Cuba ransomware is delivered via multiple vectors including phishing emails with malicious attachments, exploitation of public-facing applications, and initial access often gained through Cobalt Strike beacons or other remote access tools. It uses PowerShell scripts for execution and persistence, and leverages PsExec for lateral movement across networks. The malware terminates over 100 processes and services related to databases, backup software, and security tools to avoid detection. Cuba employs a custom encryption algorithm—combining ChaCha20 with RSA-4096—and drops ransom notes named !!!READ_ME_CUBA_RANSOMWARE!!!. Its C2 infrastructure uses hardcoded IP addresses and domains, with some samples communicating over HTTPS to avoid network monitoring. It also uses wmic and schtasks for persistence and executes a cleanup module that deletes volume shadow copies using vssadmin.

📜 History & Notable Incidents

The Cuba ransomware gang first gained notoriety in 2020 with attacks on healthcare, finance, and government entities. Notable incidents include the breach of the Clark County School District (August 2021) and the attack on the Conti-linked affiliate groups after Conti’s closure. In 2022, the U.S. CISA and FBI released joint advisory AA22-335A detailing Cuba ransomware activity. No specific CVEs are exclusively tied to Cuba, but it exploits commonly available vulnerabilities (e.g., CVE-2021-20038 for SonicWall SMA). Law enforcement actions remain limited; the group is believed to operate from Russian-speaking regions.

🔍 Detection Indicators

Known file hashes include SHA256: 2c3e9e8a7f1b... (varies per sample); behavioral signatures include deletion of shadow copies and creation of ransom notes. Network IOCs include communication with IP ranges associated with bulletproof hosting providers and User-Agent strings like 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36'. Registry keys such as 'HKCUSoftwareMicrosoftWindowsCurrentVersionRunsvhost' are used for persistence. Mutex names like 'GlobalCuba_Ransomware' have been observed.

☠️ Risk & Impact

Cuba ransomware causes severe data exfiltration and encryption, leading to operational downtime and financial losses; victims reported ransom demands ranging from $5,000 to millions of dollars. Affected sectors include manufacturing, healthcare, finance, education, and government. In 2022, FBI reported that Cuba ransomware impacted over 100 U.S. entities with losses exceeding $145 million in ransom payments and recovery costs.

🛡️ Mitigation

Recommended mitigations include enabling multi-factor authentication, segmenting networks, regularly patching vulnerabilities (especially those in VPNs and RDP), and implementing endpoint detection and response (EDR) solutions with behavioral rules. CISA advisory AA22-335A provides detection rules using YARA and Snort signatures; organizations should also back up data offline and test restoration procedures.

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