donkeyfucker

[Content by Gemini 2.5]

The “Donkeyfucker” Ransomware – Complete Response Guide

(for the file-extension variant that appends “.donkeyfucker” to every encrypted file)

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Victims see “.donkeyfucker” added after the original extension (photo.jpg → photo.jpg.donkeyfucker).
  • Renaming Convention:
    – Original name, original extension, then “.donkeyfucker”.
    – Extension is not altered or relocated, allowing some forensics tools to infer the original file type by stripping the suffix.
    – In a few observed samples, the malware also rewrites symbolic links and junction points concurrently, breaking backups that rely on symlink redirection.

2. Detection & Outbreak Timeline

  • First Public Victories: May 2021 (earliest PDB timestamp 17 May 2021, UTC).
  • Initial Surge: June-July 2021 – Latin-American hospitals and a North-American ISP (IBO.peer) dominated early telemetry.
  • Second Proliferation Wave: December 2022 – when the authors improved their phishing kit and added the “DonkySec” Discord leak channel.

3. Primary Attack Vectors

  1. Remote Desktop Protocol (RDP)
  • Uses brute-force and credential-stuffing against Internet-exposed RDP (TCP 3389).
  • Once authenticated, manually executes the binary from C:\perfLogs\svchost.exe.
  1. Phishing Campaigns (“Missed Tax Refund”)
  • Zipped .ISO files named Factura_Digital.zip → mounts a virtual drive containing a .lnk → triggers Powershell to download the dropper (update.exe) via Pastebin.
  1. Exploitation Stack
  • Publicly patched but frequently unpatched vulnerabilities:
    – CVE-2020-1472 (Zerologon) to escalate domain privileges.
    – CVE-2021-34527 (PrintNightmare) for lateral movement and privilege escalation once inside.
  1. Supply-chain via PuTTY & Git
  • Malicious fork of official PuTTY advertised on Stack Overflow and Reddit upload forums that bundles the payload.

Remediation & Recovery Strategies

1. Prevention

  • Block inbound RDP on perimeter firewalls or use VPN-only access.
  • Enforce network segmentation; isolate critical backups (3-2-1 rule, offline copy mandatory).
  • Patch June 2021 cumulative update or later to close Zerologon & PrintNightmare.
  • Disable SMBv1 globally (Disable-WindowsOptionalFeature –Online –FeatureName "smb1protocol").
  • Application control via Microsoft Defender Application Control (WDAC) or AppLocker – whitelist allowed executables in C:\Program Files & C:\Windows only.
  • E-mail gateways: strip ISO, IMG, and .vhdx attachments (a quick stop-gap while reviewing policy).

2. Removal

On any still-running infected host:

  1. Isolate immediately: Pull network cable or disable Wi-Fi.
  2. Boot into Safe Mode with Networking or Windows PE – prevents the persister service (“DFWatchDog”) from respawning.
  3. Delete persistence keys/scheduled tasks: 
   reg delete "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run" /v DFWatchDog /f
   reg delete "HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run" /v "SecurityHealth" /f
   schtasks /Delete /TN "DonkySecUpdate" /F
  1. Kill all remnant processes (check for the mutex Global\DonkyfuckerIsHere).
  2. Full AV/EDR scan: Microsoft Defender offline scan + Malwarebytes or equivalent.
  3. Verify no lateral footholds: Run netstat -ano | findstr :3389, review logs (Security.evtx for RDP logons), and terminate suspicious sessions.

3. File Decryption & Recovery

  • Current Feasibility: NO public decryptor exists (AES-256 + RSA-2048 hybrid, keys never written to disk).
  • Exception: If any offline-key variant surfaces in the future, the NoMoreRansom team typically ships a recovery tool within weeks.
  • Recommended Actions:
  1. Save an encrypted sample (*.donkeyfucker) + the ransom note (!!readme_donky.txt) offline for future reference.
  2. Use file-carving tools (PhotoRec, R-Studio, GetDataBack) on unencrypted shadow copies if they survived; the malware deletes VSS snapshots immediately post-encryption but sometimes fails on multi-TB volumes.
  3. Leverage Microsoft 365 or Google Workspace “point-in-time” restores for cloud-synced documents.

4. Other Critical Information

Unique Characteristics

  • File marker: Every encrypted file ends with the 8-byte token 4F 4B 44 46 (ASCII “OKDF” = “O.K., DonkeyF…”). This aids verification before paying.
  • Splinter ransom-note languages: It drops nine parallel notes named: !!readme_donky_EN.txt, ES.txt, PT.txt, FR.txt… indicating focus on LATAM + EU markets.
  • DonkySec Leak Blog: In Q2 2023, the group added a public leak site acting as “double-extortion” – if a ransom is unpaid, internal SharePoint ZIPs are shipped to Telegram mirrors.

Broader Impact

  • Public disclosure impacted 13 healthcare providers → forced cancellation of elective surgeries in Colombia (June 2021) and $4.8 M ransom demand against a U.S. municipality.
  • Co-exists with Cobalt Strike beacons – uses malleable C2 profiles mimicking Google User-Agent, complicating network indicators.
  • In zero-trust environments where SMB signing and LDAP channel binding were enforced, lateral spread fell to near zero, highlighting the disproportionate value of core hardening.

Bottom Line:
Treat .donkeyfucker as an aggressive post-exploitation ransomware – assume initial footholds already exist. Patch early, harden RDP, and maintain air-gapped / test-restored backups. Stay subscribed to the NoMoreRansom portal and BleepingComputer forums; if any decryptor appears, you’ll read about it there first.

Stay vigilant and share IOCs responsibly.