Full Report
The story behind the BlackMatter ransomware strain
Analysis Summary
# Tool/Technique: BlackMatter Ransomware
## Overview
BlackMatter is a sophisticated Ransomware-as-a-Service (RaaS) strain that emerged in July 2021. It is designed to target large enterprises with high annual revenues, incorporating the best features of its predecessors, specifically DarkSide and REvil. Its primary purpose is the encryption of corporate data for extortion, frequently employing "double extortion" by stealing sensitive data before encryption.
## Technical Details
- **Type:** Malware Family (Ransomware)
- **Platform:** Windows (PE), Linux (ELF for VMware ESXI)
- **Capabilities:** High-speed encryption, privilege escalation, anti-analysis, lateral movement, and data exfiltration.
- **First Seen:** July 2021
## MITRE ATT&CK Mapping
- **TA0002 - Execution**
- T1059.003 - Command and Scripting Interpreter: Windows Command Shell
- **TA0005 - Defense Evasion**
- T1027 - Obfuscated Files or Information (API hashing)
- T1497.001 - Virtualization/Sandbox Evasion: System Checks
- **TA0007 - Discovery**
- T1083 - File and Directory Discovery
- T1018 - Remote System Discovery
- **TA0008 - Lateral Movement**
- T1021.002 - Remote Services: SMB/Windows Admin Shares
- **TA0040 - Impact**
- T1486 - Data Encrypted for Impact
- T1490 - Inhibit System Recovery (Deleting Volume Shadow Copies)
## Functionality
### Core Capabilities
- **Multi-Platform Support:** Specifically tailored variants for Windows and Linux (ESXi servers).
- **Automated Encryption:** Uses a combination of RSA and Salsa20/ChaCha20 to encrypt files quickly.
- **Shadow Copy Deletion:** Executes commands to delete volume shadow copies to prevent local recovery without a decryptor.
- **Network Spreading:** Capable of enumerating network shares and encrypting files across the internal network.
### Advanced Features
- **Sophisticated Obfuscation:** Uses custom API hashing and encrypted configuration blocks to hinder static analysis.
- **Target Exclusion:** Hardcoded checks to avoid encrypting systems in specific CIS (Commonwealth of Independent States) countries.
- **Safe Mode Execution:** Capable of rebooting the machine into Safe Mode with networking to bypass security software and finish encryption.
## Indicators of Compromise
- **File Hashes:**
- *Note: Specific hashes vary per build; samples are typically around 60-70KB for the Windows version.*
- **File Names:** Randomly generated 9-character extensions (e.g., `.s8a2j9k2l`)
- **Registry Keys:** `HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run` (Used for persistence/restart during encryption).
- **Network Indicators:**
- C2 communication typically uses encrypted POST requests to attacker-controlled domains (e.g., `https[:]//mojobiden[.]com` - *example of known infrastructure*).
- **Behavioral Indicators:**
- Execution of `vssadmin.exe delete shadows /all /quiet`.
- Mass file renaming activities.
- Termination of database and security-related processes (e.g., `sql.exe`, `veeam`).
## Associated Threat Actors
- **BlackMatter Group** (Believed to be a rebrand or successor of the **DarkSide** group).
- **Affiliates:** Various unnamed cybercriminal groups specializing in initial access.
## Detection Methods
- **Signature-based detection:** Modern AV/EDR signatures for known BlackMatter packers.
- **Behavioral detection:** Monitoring for the mass deletion of Volume Shadow Copies and rapid file encryption patterns.
- **YARA rules:** Targeting the unique API hashing routine and the structure of the encrypted configuration block.
## Mitigation Strategies
- **Multi-Factor Authentication (MFA):** Implement MFA on all remote access points (VPN, RDP).
- **Offline Backups:** Maintain immutable, air-gapped backups to ensure recovery without paying the ransom.
- **Least Privilege:** Restrict administrative privileges to prevent the ransomware from spreading laterally or stopping security services.
- **Vulnerability Management:** Prioritize patching for internet-facing applications (Citrix, Exchange, VPN gateways).
## Related Tools/Techniques
- **DarkSide:** Shares significant code overlap and operational similarities.
- **REvil (Sodinokibi):** Influenced BlackMatter's configuration structure and extortion portal design.
- **LockBit:** Competitor RaaS that shares similar "double extortion" TTPs.