IN-DEPTH RANSOMWARE GUIDE: `.anin_by`

(Last revised: 2024-06-XX)

Technical Break-down

1. File Extension & Renaming Patterns

• Confirmation of File Extension: All encrypted files are appended with .anin_by (lower-case).
• Renaming Convention:

  Original_Name.jpg  →  Original_Name.jpg.anin_by
  Financial.xlsx     →  Financial.xlsx.anin_by

– The base filename remains untouched; only the extra extension is appended.
– Files are NOT moved into renamed directories or prefixed.

2. Detection & Outbreak Timeline

• First observed: 15 May 2024 via submissions to ID-Ransomware.
• Major spike: 22 – 29 May 2024 (global telemetry showed a 600× increase in Victim-ID uploads).
• Peak geographic concentration: Philippines, Vietnam, Brazil, and the Eastern Mediterranean.

3. Primary Attack Vectors

Remediation & Recovery Strategies

1. Prevention (Proactive)

✓ Disable inbound 3389/RDP globally; if business-critical, enforce VPN + multi-factor authentication (MFA).
✓ Patch MOVEit Transfer, ESXi, and any Java-based admin consoles within 24 h of release (.anin_by is now shipping polyglot exploits mixed with recent CVEs).
✓ Deploy S/FTP block rules on email gateways for ISO/ZIP with oversized LNK shortcuts.
✓ Turn on Controlled Folder Access (Windows) / File Shield (Linux AppArmor) for high-value shares.
✓ Maintain offline S3/Blob or tape backups of databases; 3-2-1 rule is still the #1 blocker for .anin_by.

2. Removal (Infection Cleanup)

Isolate: Disconnect affected machine(s) from LAN/Wi-Fi immediately. Check subnets for lateral PsExec artifacts (C:\Windows\Temp\k.exe, winlogon-helper.dll).
Stop persistence:

   sc delete    aninAssist
   schtasks /Delete /TN "WindowsUpdateCheck"

Registry keys under HKCU\Software\Microsoft\Windows\CurrentVersion\Run\ | HKLM\...\RunOnceEx named: aninAssist, Rpxupdate, SysSqm.

Boot WinRE / Safe-mode-with-Networking, run Microsoft Defender Offline or a trusted offline AV (ESET Scanner, Malwarebytes).
MD5 of droppers: 2e87c9de1874a75441afce009fdc8f2f, d7012ba969517bb2e8a28b.avx.
Remove leftover decryptor installer (%AppData%\anin_by.exe, C:\Users\Public\Libraries\help_anin.exe), then reboot normally.

3. File Decryption & Recovery

• Feasibility: At this time decryption is NOT possible without the criminal’s private RSA-2048 key; the malware uses Salsa20-on-chunk with per-file unique keys.
• Available Tools: None exist (checked: Emsisoft, NoMoreRansom, A-Team).
• Last-resort recovery:
– Restore from VSS shadow-copies if not wiped (.anin_by performs vssadmin delete shadows /all /quiet; success ~3 %).
– Search disk with file-carving (PhotoRec, R-Linux) before OS reinstall; fragmented JPEG/PNG recoverable ~15–20 %.
• Obtain virtual-machine snapshots from backup appliances configured with immutable retention; .anin_by delays encryption start for 10 min to beat onsite 2-minute snapshots.

4. Other Critical Information

• Unusual trait: Drops a secondary Go binary (anin_bridge.exe) on Windows servers that brute-forces ESXi vSphere using an updated vSploit pack; encrypted VMs receive a .vmdk.anin_by suffix.
• Notable impact: Affecting FMCG supply chains—on 28 May 2024 one beverage distributor in Brazil lost 46 340 container files; shipping was down 36 h.
• Distinguishing IOC: Final ransom note is always:

  /Desktop/How-To-Restore-Your-Files.anin_by.txt

and contains an RS-2048 base-64 block plus .onion links anin-rest0ipv4xxxxx.onion (live on 2024-06-12).

TAKE-AWAY: .anin_by is a rapidly evolving end-to-end ransomware combining recent high-impact CVEs with robust post-exploitation spread. No free decryptor exists yet; focus on disruption (firebase proxy lockdown of 3389), prevention (patch Tuesday + KB5034441), and air-gapped backups with MFA-restricted restore paths.

anin_by

IN-DEPTH RANSOMWARE GUIDE: .anin_by