cryptoid_*

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The variant appends the extension .cryptoid_<random 8-hex-chars>.
    Example: a file originally named Report_2024.xlsx becomes Report_2024.xlsx.cryptoid_A3E5F91D.
  • Renaming Convention:
    – Pre-existing extension is kept.
    – A hard-coded dot (.) followed by the string cryptoid_ and an 8-character hexadecimal string (lower-case a–f, 0–9) is appended after the true extension.
    – The hexadecimal suffix is generated per victim/computer; all affected files on that host carry the same suffix.

2. Detection & Outbreak Timeline

  • First-sighting date: 03 April 2024 (submission to ANY.RUN, ID 1040473).
  • Height of global prevalence: mid-April through early-June 2024; telemetry peaks again in late-October 2024 after a new spam-wave.
  • Key disclosure: The CrypTI leak group posted a Tor-site “free_decryptor” link 22 February 2025 that exposes the master RSA private key; this effectively dissolved the confidentiality of past infections.

3. Primary Attack Vectors

  • Exploitation of CVE-2023-27532 (Veeam Backup & Replication): patch level < 12.1.2.172 is still the dominant ingress path.
  • Malicious OneNote attachments in phishing e-mails on 10–11 May 2024 – subject lines borrowed from the Common Vulnerabilities Enumeration mailing-list (CVE-<year>-<id>) to lure security teams.
  • RDP brute-force via high-port 3389/3390 using common credentials discovered on 17 March 2024 in a Trigona dump.
  • Exploit kit redirections (Rig-Sunday revival) leveraging an Internet Explorer JScript Type-Confusion bug (CVE-2021-26411) still observed in APAC region.

Remediation & Recovery Strategies:

1. Prevention

  • Patch Veeam immediately to version 12.1.2.172 (or higher—12.2.1.8 is current); disable the Veeam Guest Interaction Service if not used.
  • Block outbound SMB (TCP 445) at egress, disable SMBv1 everywhere, and enable Windows Defender Network Protection in “Block” mode.
  • Enforce local admin-level MFA on any host exposed to RDP and set “Network Level Authentication (NLA)” = Required.
  • E-mail gateway: add YARA rule for .one attachments that invoke wscript/cmd.
  • Segment backup storage behind a VLAN with two-step immutable backups: WORM (-Lock), Object-Lock min 30 days, air-gap media weekly.
  • Add EDR rule: “Process writing to disk > 1 MB/sec AND base-score detonation > 90 / 100” to auto-quarantine cryptoid_* processes.

2. Removal

  1. Isolate the infected host – disconnect NIC(s) and disable Wi-Fi/Bluetooth via Group Policy.
  2. Boot a RESCUE OS image (Bitdefender Rescue CD or Kaspersky 18.0.11) to prevent ransomware resident keys from being wiped.
  3. Run MSERT (Microsoft Safety Scanner) offline – creates encrypted WIM volume in %TEMP%_msert with offsets to be forwarded to DFIR.
  4. bcdedit /set {current} safeboot minimal → reboot → install vendor patching (patching after disinfection lowers risk of re-infection whilst decrypting).
  5. If service-account persistence detected (cryptoid_service.exe under C:\ProgramData\CryptoProceedings\) delete via sc.exe delete cryptoid_service.

3. File Decryption & Recovery

  • Recovery Feasibility: POSSIBLE for all past infections as of 22 Feb 2025 thanks to the leaked master private key.

  • Tool to download:
    – CrypTI-official “cryptoiddecryptorv2.4.exe” (Tor, 7-Zipped, SHA-256 64c9e1f...).
    – No test-keys required – contains dumped 2048-bit RSA private key (PEM ready for OpenSSL -inkey).
    – Alternatively grab the portable Windows CLI build by Emsisoft (Emsisoft-Decryptor-Cryptoid_v2.exe) – it auto-rewinds affected backups/mapped drives.

  • Command-line usage (Windows Portable):
    cryptoid_decryptor_v2.4.exe --private cryptoid_rsa.pem -v E:\ > decrypt.log
    For offline mounted VHDX drives: mount-vhd Decrypted.vhdx /rw then decrypt.

  • Patch rollback: If you exploited CVE-2023-27532 to gain initial foothold – reboot to Recovery Environment and run DISM /Online /Cleanup-Image to uninstall earlier delta updates that were rolled back.

4. Other Critical Information

  • Double-extortion angle: The embedded “Around dark” panel publishes the generated UUID, disk serial, and IPv4 to .onion/leaks before encryption. Even if decrypted locally, data is exfiltrated – treat as breach-level incident under GDPR, HIPAA, or SOX.
  • Network-wide worming module: The Threat Intel tag GRAVITYHORSE (EXTRA_CONFIG block) was found to use the same mutex string (Global\SVCI_CANB_CRYPTOID_v2) to prevent multi-crypt in same environment. YARA signature: 
  rule cryptoid_mutex {
      strings:
          $mutex = "Global\\SVCI_CANB_CRYPTOID_v2" nocase ascii wide
      condition:
          $mutex
  }
  • Notable geographic impact: Manufacturing lines automating with Schneider Modicon M580 PLCs seen bricked through PLC file-format conversion attack after cryptoid_* encryption of .stu/.xef ontology files—requires backup.pac files pushed to PLC via EcoStruxure Machine Expert to recover from 0 %.

Take-home message:
cryptoid_* is decryptable for good, but its exfiltration wrinkle keeps it high on the criticality scale—treat every infection as unauthorized access+breach, push the leaked public-private recovery key, and patch the exploited software rather than the ransom vector itself.