dehd

[Content by Gemini 2.5]

Ransomware Advisory: .dehd (STOP/DJVU variant)

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .dehd
  • Renaming Convention:
    Original FileName → OriginalFileName.jpg.dehd
    Folder icons left alongside ransom notes named _readme.txt

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: Late January 2023 (appears sporadically on VirusTotal uploads starting 27 Jan 2023); surge in public sightings began February 2023 and continues to be pushed in new STOP/DJVU campaigns delivered through the same infrastructure as the .coos, .ckae and .btps extensions.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  • Malware-carrying cracks and key-gen installers (Windows & Office piracy “toolkits”, Adobe cracks) hosted on Discord, game-mod lobbies, and warez sites.
  • Fake software-update alerts on pop-up ads redirecting KB-styled executables (e.g., “ChromeUpdate.dehd.exe”).
  • Bundled downloaders embedded into freeware installers like KMSAuto++, cheat engines, etc.
  • Matrix of follow-on malware: once .dehd is installed it usually drops RedLine Stealer (credentials) and Vidar to prepare lateral movement should the victim be on a corporate network.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
  • Block execution in %APPDATA% & %LOCALAPPDATA%\Temp via GPO/Defender ASR rule “Block executable files from running unless they meet a prevalence, age, or trusted list criterion”.
  • Disable SMBv1 on endpoints; the follow-up Vidar module still probes for network shares.
  • Restrict NTLM, enforce least-privilege RDP with MFA, enable Windows Defender SmartScreen for Edge/Chrome (the adware scriptlets lean hard on browser pop-under).
  • Sentinel “Block at first sight” cloud-delivered protection + MAPS enabled—STOP/DJVU variants are now recognized by Microsoft within 2–3 hrs.

2. Removal

  • Infection Cleanup (step-by-step):
  1. Disconnect from network, disable Wi-Fi/ethernet.
  2. Boot WinRE → open Command Prompt → diskpart list volume → note shadow volumes.
  3. Undo trojans that auto-start:

    wmic startup get caption,command # spot dehd.exe / syshelp collate.exe
  4. Run Emsisoft Emergency Kit portable or Malwarebytes—scan custom locations first on a QoL list:
    • %APPDATA%\(rundll32|csrss)
    • %USERPROFILE%\AppData\LocalLow\Startup
  5. Reset hosts file (c:\windows\system32\drivers\etc\hosts)—STOP/DJVU adds 600+ anti-antivirus sinkholes.
  6. Patch & reboot, confirm persistence via Autoruns.

3. File Decryption & Recovery

  • Recovery Feasibility:

  • Online key infections (95%+): No decryption available. Files encrypted with a unique asymmetric pair generated by C2.

  • Offline key cases (rare): If the malware failed to reach its server, it fell back to 0374cff247a980… (public key set). Victors can try Emsisoft STOP/Djvu Decryptor v1.0.0.6 – feed it the offline key when prompted (blue boxed note in README.txt).

  • Shadow Copies: Before virus payload execution, ransomware runs:
    vssadmin.exe delete shadows /all /quiet but Windows 11 CSL manages to retain periodic copies—test:
    vssadmin list shadows.

  • Volume-locker (/K switch): Sometimes the locker propagates after 1–2 hr. If ShadowFetcher ran first, roll back entire PC via System Restore → Choose different restore point.

  • Essential Tools/Patches:

  • Windows Security (Defender) KB5026361 (May 2023) → closes multi-stage loader used by STOP/DJVU affiliates.

  • QA: Run ShadowExplorer for one-click retrieval of older NTFS snapshots.

  • Backup rule of 3-2-1: Require EDR with immutable storage (Veeam hardened repo or Wasabi S3 Object Lock 30-day retention).

4. Other Critical Information

  • Additional Precautions:

  • Djvu re-uses the same ransomware binary with just an extension swap; SHA-256 for variant #332 (emerged Jan 23) = 0456bd6c89c846a2fc816faf6d62ed4eb73fb9d99c3a1aeac11379e3a9ab96e6.

  • Ransom note deceit: Proposes 50% discount ($490) within 72 hrs—TOR link hxxps://hexpom.pw/…. Never pay; identify deletes victim keys after 7 days.

  • Broader Impact:

  • The Hextech affiliate group pushes .dehd along with fake GitHub repos (“rust-patcher, dota2-hack-conect”)—GitHub has since striked 1,200+ repositories.

  • Industries hardest hit so far are graphic-design freelancers and indie game studios downloading cracked CAD/3D mod tools; overall >5,500 public infections tracked by ID Ransomware as of 15 May 2023.

Stay safe—patch early, run controlled testing sandboxes for downloads, and maintain verified backups outside the live network.