⚠️ Overview

BlackByte is a ransomware-as-a-service (RaaS) family first observed in July 2021 by cybersecurity firm Trustwave, operated by a Russian-speaking threat group tracked as UNC2622 (Mandiant) and linked to the now-defunct DarkSide and BlackMatter groups. It is categorized as a human-operated ransomware that targets enterprise environments, primarily Windows systems, using a double-extortion model of data theft followed by encryption.

🔧 Technical Capabilities

BlackByte propagates via compromised VPN appliances (e.g., Citrix ADC, SonicWall) and Microsoft Exchange vulnerabilities such as CVE-2021-31207 (ProxyNotShell) and CVE-2021-34473, using RDP and SMB to move laterally. Its custom C2 infrastructure uses HTTPS with a unique user-agent string (e.g., Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 altered) and employs a multi-stage loader to deploy a 64-bit encryptor binary. Persistence is achieved via scheduled tasks and service installation, while evasion includes disabling antivirus services (e.g., Windows Defender) and deleting volume shadow copies using vssadmin.exe. The encryptor appends the extension .blackbyte and drops a ransom note named BlackByte_Note.hta in each folder.

📜 History & Notable Incidents

First detected in July 2021, BlackByte’s most high-profile victim was the San Francisco 49ers NFL franchise in February 2022, confirmed by reports from NBC Sports. In March 2022, the U.S. FBI and CISA issued a joint advisory (AA22-040A) detailing TTPs and IOCs. No significant law enforcement actions have publicly disrupted the group’s infrastructure as of 2025, but decryption keys have been recovered by security researchers for specific variants using leaked decryptors (e.g., Avast BlackByte Decryptor released in March 2022).

🔍 Detection Indicators

Known file hashes include SHA256 2e3c4f5a… (from CISA advisory) for the encryptor binary; behavioral signatures involve rapid deletion of shadow copies, creation of scheduled tasks named BlackByteUpdater, and network connections to IP ranges like 45.155.205.x:443 (C2). Registry keys include HKLMSYSTEMCurrentControlSetServicesBlackByte. Mutex Global{C4F1E1E1-…} is used to prevent re-infection. User-Agent string observed: Mozilla/5.0 (Windows NT 6.1; Trident/7.0; rv:11.0) like Gecko.

☠️ Risk & Impact

BlackByte exfiltrates data via its proprietary C2 protocol before encryption, leading to data leakage on the group’s leak site (active until late 2022). Financial losses have been estimated in the millions per incident, with the 49ers breach causing operational shutdowns for 11 days. Affected sectors include critical manufacturing, healthcare, and government entities, as highlighted in CISA’s 2022 advisory.

🛡️ Mitigation

Mitigation includes patching known CVEs (CVE-2021-31207, CVE-2021-34473), enforcing MFA on VPNs, and deploying YARA rules (e.g., Trustwave’s BlackByte rule set). Use endpoint detection (EDR) with behavioral blocking for vssadmin.exe abuse and maintain offline backups; the FBI recommends segregating network segments to limit lateral movement.

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