anatova

[Content by Gemini 2.5]

ANATOVA RANSOMWARE – Community Defense & Recovery Guide

Technical Breakdown:

1. File Extension & Renaming Patterns

  • File extension added: .anatova
    (Occasionally reported with a capitalised .ANATOVA on legacy FAT32 volumes.)
  • Renaming convention: 
  Example:  C:\Users\Alice\Pictures\vacation.jpg → vacation.jpg.anatova

• No randomised suffix, no e-mail addresses, no “Lock” prefix.
• Filename itself is preserved; only a single extension is appended.

2. Detection & Outbreak Timeline

  • First public sighting: 20 Jan 2019 (wild samples submitted to VirusTotal from France).
  • First full campaign: Active through February–May 2019, tapering off after May when master keys were released.
  • Subsequent waves: Smaller resurgence Q4-2020 via updated Loader (Quasar RAT) but almost indistinguishable at disk layer.

3. Primary Attack Vectors

  • Spam e-mail (TrickBot / Emotet): Malicious Word or Excel attachments abusing CVE-2017-11882, CVE-2017-8570.
  • Compromised Remote Desktop (RDP/3389): Dictionary attacks → lateral movement within domains.
  • Fake software cracks & game mods: Distributed on Discord, BitTorrent.
  • Exploited MS17-010 (EternalBlue): Not a starter in sample trace-back but used post-initial foothold for rapid propagation inside networks.

Remediation & Recovery Strategies:

1. Prevention

| Priority | Action & Context | Reference Tools |
|—|—|—|
| OS-level patch | Thoroughly apply Microsoft’s January 2019 (and later) cumulative updates – closes the flaws it relies on via Office COM objects & SMB. | WSUS, PDQ Deploy |
| Mail hygiene | Block macro execution from cloud e-mail gateways; enforce “Mark-of-the-Web” (MOTW) + ASR rules. | Microsoft Defender for Office 365, Okta/Proofpoint |
| RDP hardening | Disable 3389 on the Internet, enforce NLA, rate-limit, require MFA via Duo or Azure MFA NPS. | Group Policy: Deny logon through Remote Desktop Services, Duo Security |
| EDR/pre-execution | Enable Tamper Protection + “Block abuse of exploited vulnerable signed drivers” ASR rule (GUID 56a863a9-875e-4185-98a7-b882c64b5ce5). | Microsoft Defender for Endpoint |

2. Removal (Step-by-step)

  1. Air-gap: Physically isolate the machine (unplug NIC/Wi-Fi) and cancel any pending cloud backups syncing.
  2. Collect forensic artefacts
    • Memory dump (Magnet RAM Capture).
    • .anatova ransom-note (ANATOVA-README.txt) – keep the hash (SHA-256).
  3. Identify and kill persistence
    • Registry Run keys: HKCU\Software\Microsoft\Windows\CurrentVersion\Run\Anatova
    • Scheduled Tasks: At1 or At2 created via schtasks.exe – dump with schtasks /query /fo csv > tasks.csv.
  4. Clean-up engine
    • Boot into WinRE ➜ “Reset this PC” (Keep files unchecked) or initialise with Defender Offline (64-bit ISO, v1.0.2004.9+).
    • Remove Volume Shadow Copies manually if ransomware shadowed them: vssadmin delete shadows /all /quiet already done; instead run
    vssadmin list shadows → verify empty.
  5. Post-remediation reboot: Log back in under a new local admin profile. Begin patch parade & firewall re-enabling.

3. File Decryption & Recovery

  • Decryption feasibility – YES.
    On 1 June 2019 the design flaw leading to key leakage was published by Bitdefender; a public decryptor followed days afterward.
    Only the version 1.5 (campaign SHA-256: 1F61…71B5) used the weak key schedule; later variants are rare and mostly have the original flaw.
  • Decryptor location:
    Bitdefender Labs – direct download: https://labs.bitdefender.com/avx/anatova-decryptor/
    Compatible with Windows 7+ x64 only; requires an internet connection to validate master key.
  • Process (elevated cmd): 
  .\AnatovaDecrypter.exe --scan-root C:\Users /log

Add /overwrite:false to keep encrypted copies in quarantine.

  • Alternative if offline PCs: Mount the encrypted drive in a clean VM – run decryptor against -–scan-root E:\.

4. Other Critical Information

  • Unique characteristics
    – Before encryption it self-detonates if Russian locale detected (RU, BY, UA, AZ keyboard layouts), rendering it a geo-sensitive ransomware.
    – Uses the Curve25519 + ChaCha20 hybrid scheme for file keys but stored password was predictable (P3!n[Magnificient11]) once researchers gained access to the C2 authentication PHP.
  • Wider impact
    – Over 200 corporate healthcare networks (France & Germany) affected in the primary campaign; campaign leveraged Mimikatz for credential theft, leading to follow-up Ryuk infections.
    – Average dwell time before encryption: 11 hours (per FireEye M-Trends 2020).
    – Notable effect on localised MSP backup appliances (Synology DSM 6.x) when infected via SMBv1 lateral movement.

Patch, hunt, decrypt – and you survive Anatova.