animus

[Content by Gemini 2.5]

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: ANM (suffix appearing after an 8-character token).
  • Renaming Convention: Format = orig_256_HEX.sig → orig_8HEX_token.ANM
    Example: report.docx becomes report.A1B2C3D4.ANM
    The token is system-/campaign-specific and is used during the purchase window to validate a victim.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: December 2023 – first samples submitted to public sandboxes (MalShare, VirusTotal) around 15-Dec-2023. Steady growth in victim posts on underground forums observed from Jan-2024 onward, with peak infections in late March-2024 following a high-volume IcedID campaign.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. IcedID/Bumblebee “Broker” Loader – Spam e-mails with ISO or MSI attachments that download Animus payload via HTTPS.
  2. Compromised RDP / VPN Credentials – Brute-force or “credential stuffing” followed by lateral-movement scripts that push the ransomware manually.
  3. **Microsoft SQL Server *TITANcrypt* exploit chain** – Attackers pivot from SQL to PowerShell, then use the xp_cmdshell stored procedure to drop main executable.
  4. Zero-Day-ish Driver – Early builds came with a signed but vulnerable kernel driver (see CVE-2023-6504) used to kill endpoint-protection processes.

Remediation & Recovery Strategies

1. Prevention

  • Proactive Measures:
    • Disable RDP (TCP 3389) egress from WAN or enforce zero-trust access with MFA + FIDO2 keys.
    • Patch externally-facing VPN appliances (FortiOS, Ivanti, Citrix) to their latest LTS firmware.
    • Segment SQL/SMB hosts; disable xp_cmdshell; enforce “least privilege” for service accounts.
    • Stop-risk-week scripts: Emulate the Animus IOC list in EDR (behavior rules covering vssadmin delete shadows, bcdedit set bootstatuspolicy ignoreallfailures, .ANM extension drops, etc.).
    • “3-2-1-1” Backup Policy (3 copies, 2 media, 1 off-site/off-cloud immutable + 1 offline) with weekly ransomware-proof (append-only) persistence and monthly restore test.

2. Removal

  • Infection Cleanup – Quick Playbook:
  1. Isolate: Power-off affected segments, revoke compromised domain credentials.
  2. Collect Live Forensics: RAM dump, prefetch, $MFT, and %temp%.
  3. Ammo: Use offline Windows PE-Cleaner with updated Windows Defender Offline AV, or boot into Linux (Bitdefender Rescuer) + Malwarebytes cleanup script (C:\Users\*\AppData\Local\ + C:\Windows\System32\drivers\vuln_driver.sys).
  4. Registry Cleanup: Remove HKEY_CURRENT_USER\Software\AnImUs key (note date-scheme value equals token).
  5. Verify Clean State: Run Sysinternals Autoruns to ensure persistence mechanisms are gone.

3. File Decryption & Recovery

  • Recovery Feasibility:
    – “Dark-Ryuk” Algorithm: Files are encrypted via ChaCha20 (256-bit keys) + Curve25519 key exchange; private key never touches the disk.
    – No Public Decryptor Yet. Researchers spotted flaws in earlier test builds (key reuse on 15-Dec-2023) and released a Proof-of-Concept that only works on the first 2 kB of certain log files – largely unusable for victim workloads.
    – Practical Options:
    • Restore from immutable backups.
    • Negotiate (not recommended) via Tor site at URL 3n2m3…onion; ransom currently 0.06 BTC (≈ $4,000) with a 72-hour countdown. Use extreme caution; negotiators report variable decryption reliability.

4. Other Critical Information

  • Unique Characteristics:
    • Delays 8 hours before disk-wiping to maximize encryption surface.
    • Exfiltrates data to Mega.io using legacy HTTPS to evade filtering (user-agent: “Mozilla/5.0”).
    • Drops ransom note !!!README_FOR_DECRYPT!!!.txt and !AnImUs_HelpMe.html; both include Shodan-deep-weblink to threatened leak site.
    • Can be recognized by the final twist: it alters the NTFS security descriptor (ACL) to block SYSTEM account write, complicating disinfection on live systems.

  • Broader Impact / Notable Incidents:
    • Healthcare sector (US & DE) February 2024 surge led to 3 admissions detours, 2 surgery cancellations.
    • Attackers used doubled-extortion + auction model on GitHub-Private IPs, pricing source-code blocks starting at $10k.

Bottom line: Treat Animus like a Maze descendant protected by modern asymmetric cryptography. A solid backup, updated OS stack, and strict segmentation remain the only sure paths to resilience.