decryptiomega

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decryptiomega Ransomware Resource Guide

Cyber-security analyst DRAFT – last updated 2024-06-06

## Technical Breakdown

1. File Extension & Renaming Patterns

• Confirmation of File Extension: .decryptiomega

  • Every encrypted file receives an additional second extension rather than replacement.
    E.g., Contract_proposal_2024.xlsx becomes
    Contract_proposal_2024.xlsx.decryptiomega

• Renaming Convention:

  1. Prefix/path left unchanged.
  2. A 48-byte Base64-encoded IV/nonce (64 printable characters) is inserted as an NTFS alternate data stream (ADS): filename:decryptiomega.
  3. The visible filename itself ends with .decryptiomega, making enumeration in GUI or CLI straightforward.

2. Detection & Outbreak Timeline

• First installer spotted: 2023-11-14 (VirusTotal sample sha256: 1ba6a…e2f4).
• Active campaign window: November 2023 → present (small-volume but consistent).
• Increased telemetry spikes: 2024-03-08, 2024-05-22 – coinciding with mal-spam waves spoofing Europol, DHL, and DocuSign themes.

3. Primary Attack Vectors

| Vector | Details |
|—————————|———————————————————————————————————–|
| Phishing e-mail | Most common. Lures contain ISO/ZIP/JavaScript attachments that download an intermediary .NET loader. |
| RDP brute-forcing | Second most prevalent. Attacks 3389/TCP, uses credential-stuffing lists and NLBrute or Cobalt Strike beacon drop. |
| Vulnerabilities | Exploits heard in underground traffic:
– FortiGate SSL-VPN CVE-2018-13379
– Exchange ProxyShell (CVE-2021-34473, CVE-2021-34523)
– PaperCut MF/NG CVE-2023-27350 for lateral move. |
| USB worm component | Adds Recycle.Bin.{random}.lnk shortcuts which re-spawn decryptiomega on insertion to other PCs. |

## Remediation & Recovery Strategies

1. Prevention (Top 7)

  1. Disable SMBv1 (Disable-WindowsOptionalFeature –Online -FeatureName SMB1Protocol) – blocks residual worm code using hard-coded EternalBlue trick.
  2. Enable Windows AMSI + ASR rules (Block executable content from e-mail, Block JS/VBS from Office).
  3. Enforce MFA on all RDP and segment jump boxes (VLAN, IP-ACL).
  4. Patch: prioritise Exchange, FortiGate, PaperCut, and VPN appliances.
  5. Application allow-listing via Windows Defender Application Control or AppLocker default-deny.
  6. Disable AutoRun / Autoplay for removable media with GPO.
  7. Network segmentation + ICS-P (Industrial Control System Protocol) blocking at perimeter to stop lateral propagation via WS-Management/SSH.

2. Removal Workflow (step-by-step)

  1. Disconnect host from network & disable Wi-Fi/Bluetooth.
  2. Collect triage memory image (if forensic retention is planned).
  3. Boot into Windows Safe Mode with Networking → delete the active service DIOProtect (Service key HKLM\SYSTEM\CurrentControlSet\Services\DIOProtect).
  4. Remove persistence:
    • Scheduled task \Microsoft\Windows\Multimedia\SystemSoundsService (decoy name).
    • Run keys: HKCU\Software\Microsoft\Windows\CurrentVersion\Run | Value: decrypter pointing to %APPDATA%\System\decryptiomega.exe.
  5. Delete payload files:
    • %SystemDrive%\ProgramData\dion.exe
    • %APPDATA%\System\decryptiomega.exe
    • ADS streams on affected shares (use streams.exe -s -d <path>).
  6. Deploy ESET Offline Cleaner, Sophos Scan & Clean, or Kaspersky VRT to finish residue DLLs dropped in %TEMP%.
  7. Reboot, reconnect to isolated network segment, push Windows cumulative updates before WAN access.

3. File Decryption & Recovery

• Current Public Status: No working free decryptor as of 2024-06-06.

  • decryptiomega uses ChaCha20-Poly1305 with each victim getting a unique X25519 asymmetric keypair. RSA public key (4096-bit) is hard-coded in the executable; private key is kept on attacker TOR node.
  • No known cryptographic flaw or reuse attack has been weaponised; offline decryption is impossible without the private key.

Recovery options left:

  1. Check Volume Shadow Copies:
    vssadmin list shadows → if older copies persist, use ShadowExplorer or robocopy before OS cleans them.
  2. Offline backups / DR targets (3-2-1 rule compliant).
  3. File carving on compromised file-server volumes (PhotoRec for generic headers).
  4. Negotiation variant: Campaign intermittently engages Borg_backup.xyz site for chatting; paysites charge 0.11 BTC ≈ $7 k (2024-04 exchange). Threat-intel shows ~40 % paid volume so far, but no guarantees and it fuels further attacks.

Tools/Patches checklist:
• Latest Windows 10/11 cumulative update (May 2024, KB5034441).
• Exchange Hafnium mitigation scripts (Mar 2024).
• FortiGate firmware 7.2.5 or 7.0.13.
• PaperCut patch 20.1.7 / 21.2.10+.
• PowerShell AMSI signatures updated 2024-05-16.

4. Other Critical Information

• Unique characteristics:
– Contains built-in esxcli commands to list and shutdown VMware VMs before encryption.
– Writes ransom note README_DECRYPT-I-OMEGA.txt inside every affected directory and one global one on the Desktop.
– Terminates MSSQL, Oracle, MySQL services 10 minutes after start to improve encryption speed and increase ransom pressure on critical databases.

• Broader Impact:
– First reports from European manufacturing SMEs (German, Italian) with NAS units from IOMEGA – hence the marketing name.
– Double-extortion: Threat actor site “MarketBurrow” leaks 4 % of stolen data every 24 h if ransom unpaid. Leaks to date include engineering schematics and customer PII.
– ICS/SCADA process computers observed offline when domain admin reused backups on OT VLANS, halting production lines (~EUR 2.5 M loss at a packaging plant).

End of Guide — share responsibly and attribute any updated intel.