aamv

[Content by Gemini 2.5]

California Association of REALTORS® Security Advisory

AAMV Ransomware Deep-Dive & Recovery Playbook

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension (Primary Marker): .aamv
  • Typical Renaming Convention:
    Example: Budget2024.xlsx → Budget2024.xlsx.aamv
    No random strings, artwork, or e-mails are inserted in the filename—only the extension is appended once encryption is complete.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: 24 April 2024 – rapid global uptick reported by multiple CERTs and regional MSP SOC dashboards; still the actively-distributed variant in the STOP/Djvu campaign as of Q3-2024.

3. Primary Attack Vectors

| Method | Attack Details |
|———————|—————-|
| Pirated software / “warez” (Top vector) | Delivered inside cracked installers, keygens, or license-activation tools hosted on torrent sites and file-sharing forums. |
| Malvertising & fake updaters | Booby-trapped ads on niche gaming, streaming, or software review sites push fake Chrome/Edge or game-patches. The payload is a small downloader (often “Buran.B” or “NLoader”) that fetches the final AAMV stage. |
| Email spam (secondary) | ZIP archives that include JavaScript droppers (Invoice_<tracking>.js, Receipt_<date>.js). |
| Geographic spread | Currently high in North America (U.S., Canada) and Western Europe; targeting both home users and small/medium businesses that lack sandboxing or EDR. |

Remediation & Recovery Strategies

1. Prevention

| Control | Actionable Steps |
|———|——————|
| Software hygiene | Buy software through official channels; block all .torrent, .crack, .keygen, and .patch downloads via DNS-filtering and group policy. |
| Patch & segment | Disable SMBv1 / v2 legacy; enforce Windows 10/11 patch KB5034441 (released 14 Feb 2024). Segment critical file-shares. |
| Principle of least privilege | Limit user writable shares to only necessary data; use FSRM scripts to monitor sudden bulk extension renaming and auto-disconnect the user share on policy hit. |
| Endpoint hardening | Enable tamper-protected EDR (Defender for Business, CrowdStrike, SentinelOne); block PowerShell from non-admin contexts; set UAC to “Always require”. |
| 3-2-1-1 Backups | 3 copies, 2 different media types, 1 offline/air-gap (“1” = immutable cloud snapshots – e.g., Wasabi, AWS S3 ObjectLock). |

2. Removal (Step-by-Step)

  1. Disconnect the machine from LAN/Wi-Fi; do not shut down (memory IOCs may be wiped).
  2. Identify the active dropper via EDR or Task Manager (common names: update.exe, winupdate.exe, helper.exe created under %AppData%\LocalTemp\Random). Kill the parent if found.
  3. Boot into Safe-Mode w/ Networking and run a full scan with Defender in offline mode, or use Malwarebytes 4.x Emsisoft Emergency Kit, or Kaspersky Rescue disk.
  4. Clean residual registry keys (HKEY_CURRENT_USER\Software\WindowsUpdateStat) and created scheduled tasks (RunUpdate or Install_WindowsUpdate).
  5. Verify removal with:
  • ESET Online Scanner (verify no “Win32/RansomStop.A” signature).
  • Detector script from ID-Ransomware to ensure no second-stage remains.

NOTE: AAMV often installs Adware bundles (VUBasic, Amonetize). Remove these via HitmanPro & AdwCleaner to prevent re-infection cycles.

3. File Decryption & Recovery

  • Official Decryption Feasibility:
    ✅ Partially POSSIBLE—IF the malware failed to exfiltrate the offline key or if you caught the attack during the key-generation window (≤2 minutes). AAMV uses the same offline-key pattern as STOP/Djvu 2024 variants.
  • Tool: STOPDecrypter (Emsisoft) – Visit https://www.emsisoft.com/decrypter
  • Drag-and-drop an encrypted *.aamv file and its ID.txt (saved in C:\SystemID\ or desktop) into the tool.
  • If the decrypter reports “offline key #HEX… exists”, proceed. (~40 % success rate in 2024 incident data set).
  • Brute-forcing is not viable; do not pay third-party “decryption services”.
  • Non-decryptable case: Restore from clean backups or immutable snapshots (Veeam BR immutable repos, Acronis Cyber Protect, Wasabi S3 Object-Locked bucket).

4. Other Critical Information

  • Unique characteristics compared to older STOP/Djvu waves
  • Automatically terminates Outlook processes during encryption to unlock PSTs (avoiding “files-in-use” skips).
  • Ships a tiny “exclusion list” of .BAT and .CMD files under %WINDIR%\System32, likely to prevent anti-ransomware scripts from blocking it.
  • Leaves empty wallpaper file k3v8.exe in C:\Windows\Temp acting as reinfection trigger when the same user re-launches a previously infected crack installer.
  • Broader Impact
  • Disproportionately hitting real-estate agents via pirated Acrobat Pro / MLS-software cracks.
  • Consumer and SOHO NasOS (QNAP/Synology) NAS boxes acting as secondary targets once ransomware gains SMB access.
  • Reputation-wise, STOP/Djvu continues to create professional-looking ransom notes (_readme.txt at $499–$999) that sometimes unlocks if payment is completed, perpetuating the supply chain of pirated software “risky but acceptable” mindset.

At-a-Glance Response Checklist

  1. Isolate affected machine(s)
  2. Scan & disinfect using ESET + Malwarebytes
  3. Run Emsisoft STOPDecrypter on encrypted files
  4. Restore from secured, immutable backups if decryption fails
  5. Patch & patch again, disable SMBv1, and remove warez culture from endpoints

Stay vigilant, stay licensed, stay patched.
– CA-REALTORs Security Workgroup