domn

[Content by Gemini 2.5]

Comprehensive Defense & Recovery Guide

Ransomware Variant: DOMN

Associated file-extension observed on disk: .domn

1. Technical Breakdown

1.1 File Extension & Renaming Patterns

  • Exact Extension: .domn (all lower-case; no preceding dot in the ransom note — the dot only appears on the last part of the filename).
  • Renaming Convention: 
  <original_full_filename>.<original_extension>.<unique_id>.<email_tag>.domn

Example: 

  AnnualReport_Q3.docx.A1B2C3D4.example[@]aol.com.domn
  • "A1B2C3D4" is a 6- to 12-character hexadecimal victim-ID generated during key exchange.
  • "example[@]aol.com" is the attacker-controlled email used for negotiation.
  • All extra metadata is preserved, so users can still identify what file they are looking at.

1.2 Detection & Outbreak Timeline

  • First samples seen in open repositories: 2 Oct 2019 (BleepingComputer Forum, ID-Ransomware).
  • Peak infection surge: Mid-October to December 2019, quickly expanding to French, German, Italian, South-American and South-East Asian victims.
  • Active STOP/Djvu v0162 branch still encounters .domn infections today, especially via cracked software and torrents.

1.3 Primary Attack Vectors

| Vector | Details & Mitigation Notes |
|—|—|
| Spam / Phishing emails | Malicious ZIP or ISO attachments containing NSIS installer bundles. |
| Malvertising & Porn-site redirect chains | Leads to RIG / Fallout exploit kit before downloader MSI is served. |
| Cracked/Bundled software | Windows activator tools (KMSAuto, Re-Loader), game cracks, Adobe, AutoCAD. Most prevalent delivery mechanism today. |
| Exploit kits | Uses CVE-2018-0824 (Windows VBScript), CVE-2018-15982 (Adobe Flash), SMBv1 was never used. |
| RDP | Brute-force or purchased access sold on Genesis; lateral propagation via stolen credentials not typical – victims are usually single-host. |

2. Remediation & Recovery Strategies

2.1 Prevention

  • Patch & Update
  • Adobe Flash (or uninstall), Windows Scripting host permissions, latest Windows cumulative updates.
  • Maintain offline system-image backup at least weekly and daily cloud replication.
  • Email & Endpoint
  • Disable Office macros by GPO.
  • Block executable and script files from %appdata% and %temp% execution via AppLocker/SRP.
  • Enable Windows Defender ASR rules (Block Office apps creating executable content, Block credential stealing, etc.).
  • User Policy
  • Institute a zero-cracks policy – STOP/Djvu (and thus DOMN) payloads are overwhelmingly delivered via pirated software.
  • DNS sink-hole known Djvu C2 (91.207.175 d0mains, vpn DDos Guard domains) through Pi-hole or enterprise DNS tools.

2.2 Removal – Step-by-Step

  1. Isolate the infected computer – unplug Ethernet/Wi-Fi immediately.
  2. Boot into Safe Mode With Networking. This will prevent Salsa20 encryption routine from auto-starting.
  3. Run Rkill to terminate malicious processes.
  4. Clean® disk with either:
  • Malwarebytes
  • ESET Online Scanner
  • Emsisoft Emergency Kit (paid license adds full cleanup mode)
  1. Remove registry persistence: 
   HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\SysHelper

and scheduled tasks named:

   explorer.exe <random>.exe
  1. Patch any exposed accounts & rotate passwords: if you don’t re-image you must treat password compromise as certain.

Note: STOP/Djvu variants do drop additional info-stealers (Vidar, Amadey, AZORult). Assume exfiltration of browser credential stores.

2.3 File Decryption & Recovery

  • Online vs Offline Key
    STOP/Djvu uses a 256-bit key pair; the copy of which is ONLY stored on attacker server for online attacks.
    Therefore decryption requires possession of the attacker’s private key (impossible for most online victims).
  • Decryption possible IF Machine was offline at the time of infection OR you find a decrypted readme.txt advising an offline key.
  • Tool: Official, continuously updated decryptor by Michael Gillespie (Emsisoft) – grab the file named decrypt_STOPDjvu.exe.
  • Run with elevated PowerShell:

    decrypt_STOPDjvu.exe C:\
  • Provide any working/clean sample file pair (same file before/after encryption) for verification of offline key.
  • No key = No tools left. Standard recovery: revert from cold backup first, shadow copies are wiped.

2.4 Essential Patches / Software Updates

  • Windows Script Engine update (KB5005568 2021-09) – mitigates payload dropper scripting.
  • Adobe Flash Player 32.0.0.344 (2019-11) — final version before EoL; remove if still installed.
  • 7-Zip 22.00+ or WinRAR 6.11+ to inspect unknown archives rather than double-clicking.
  • Latest Malwarebytes / ESET / Windows Defender signatures (last stable build Jan 2024).

2.5 Unique Characteristics & Broader Impact

  • Multi-info-stealer bundled model – DOMN variant historically delivers Vidar Stealer minutes after the encryption completes. This leads to double damage:
    – Crypto-ransom
    – Credential & Crypto-wallet theft.
  • Djvu Carding Ecosystem – Private keys allegedly resold for 980 USD (discounted to 490 USD promo). Security researchers collect these keys; decryptor grows roughly once per month.
  • No major kill-switch or campaign shutdown event – its distribution relies on pirated software market, shifting with MFA protected file hosts such as BiT-Torrent clients. Expect persistence indefinitely.

Closing Note

Victims normally face two simultaneous threats: (1) ransom demand and (2) data breach via the bundled trojans. Restore from backup, never pay, but always reset every credential that was ever stored in the affected profile.