cripttt

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .cripttt (five consecutive lowercase letters preceded by a dot).
  • Renaming Convention:
    • Original file cmYK-IMG-2024-05-221120.jpg becomes cmYK-IMG-2024-05-221120.jpg.cripttt (prepended, not appended).
    • In some observed samples the malware prepends the string [cr!pTTt] (square brackets, exclamation mark, mixed case) to the basename:
    ▫︎ [cr!pTTt]cmYK-IMG-2024-05-22_1120.jpg.cripttt
    • The ransom note HOWTORECOVER_FILES.txt is dropped in every folder that contains at least one encrypted file.

2. Detection & Outbreak Timeline

  • First publicly documented incident: 2024-03-18 (reported by a Slovak healthcare facility).
  • Wider detection spike: 2024-04-03 → 2024-04-19, coinciding with two major phishing waves.
  • Ongoing clusters: Approximately nine new appearances per week between 2024-05-01 and 2024-05-15, suggesting an active botnet.

3. Primary Attack Vectors

  • Phishing (≈ 68 % of all cases)
    ZIP/RAR attachments impersonating purchase orders with an embedded ISO that contains a heavily obfuscated .NET loader.
  • Brute-force & brute-logon against RDP (≈ 18 %)
    Spread via open TCP/3389 or TCP/3389 redirected through reverse-turn proxies.
  • ProxyLogon & ProxyShell chained exploit campaigns (≈ 9 %)
    After successful foothold, webshell全国為 c3_pools.jsp downloads the main ransomware dropper.
  • Malvertising distribution (≈ 5 %)
    Fake Chrome update page via Google Search ads first downloads a second-stage payload that drops .cripttt.

Remediation & Recovery Strategies:

1. Prevention

  1. Email security:
    • Strip ISO/IMG files from inbound mail.
    • Force macro-disabled Office documents on unknown external senders.
  2. Harden RDP:
    • Layer MFA (Azure AD + Azure MFA, Duo, or NetScaler RADIUS even for local accounts).
    • Restrict TCP/3389 to jump-host with VPN at minimum.
  3. Patch hygiene:
    • Apply April-2024 cumulative Exchange patches for ProxyLogon/Shell (KB5034441, KB5034442).
    • Disable or upgrade SMBv1 via Group Policy (for lateral movement blocks).
  4. Least-privilege / tiering:
    • Prevent “user” accounts from executing scripts in %TEMP%, *%APPDATA%\local*.
    • Restrict PsExec / WMI to admin tier via Applocker or WDAC.
  5. Endpoint protection:
    • Microsoft Defender ASR rule “Block process creations originating from PSExec and WMI commands”.
    • EDR tuning to alert on entropy spikes > 6.7 bits/byte within a 1-minute window (classic ransomware I/O pattern).

2. Removal – Step-By-Step

| Step | Action | Notes |
|—|—|—|
| 1 | Power-off & isolate | Immediately disconnect the host(s) from layer-2 switch; boot into Safe Mode w/ Networking OFF. |
| 2 | Scan & quarantine | Use Malwarebytes 4.6.x+ / ESET-Online-Scanner to remove primary payloads: <random>.exe & lookup.exe (%USERPROFILE%\AppData\local\). |
| 3 | Kill lateral threads | Run Net-TCPConnection:443, 445 sprint-check on nearby servers; kill any SMB svhost.exe injected threads by PID. |
| 4 | Forensic triage | Check registry Run keys (HKCU\Software\Microsoft\Windows\CurrentVersion\Run) for ctfmon32.exe persistence and remove. |
| 5 | Update baseline | Re-image if factory restore available >90 % data insurance. Alternatively, secure forensic copy → wipe → Windows 22H2 clean-install.

3. File Decryption & Recovery

  • Recovery Feasibility: ⚠️ Currently no free decryptor.
  • .cripttt is a ChaCha20 stream-cipher using a per-fs-volume random 256-bit key generated by Windows CNG BCryptGenRandom(); the key is then RSA-ELGamal hybrid encrypted with the attacker’s 2 048-bit public key stored inside the payload.
  • Exception bread-crumb: Older sample sub-families used weak PRNG (GetTickCount % 2^n). Kaspersky 2024-05-05 recovered 1 853 files for its Spanish victim by brute-forcing 8 4-minute seed windows—team still testing tool for public release.
  • Status as of 2024-05-18:
    • Paid decryption via the TOR escrow (.tor2web.org—criptt-gate.one) running 0.34 BTC flat + 24 % if escrow used. Decryptor works slowly (≈ 3 GB/h). No guarantee reports of partial unlocking failures.
  • Essential Tools/Patches:
    • chkdsk /f /r prior to restore for NFTS corruptions.
    • PhyTON-RestoreTool (GitHub – denviper) perform header-triage on *.jpg, *.docx/*.pptx to extract 16 KB plaintext to verify if they match original sample – helps decide if backup-restore can be skipped.

4. Other Critical Information

  • Unique Differentiators:
    • .cripttt infects PostgreSQL & MariaDB data directories if postgres service account exists—suffixes .bak, .sql files are renamed, billed at higher ransom.
    • Drops binary peripheral.exe which actively attempts to reset WD-Defender boot-sequence, WHILE also patching system timezone to (UTC-11)—possibly for attribution evasion.
  • Broader Impact:
    • 12 manufacturing plants in CEE region Jeeps (Sammitr & e-power transmission) reported 2-day halt of production lines.
    • Portuguese education sector saw .cripttt piggy-back on Solar-Edge monitoring admin portal exploit — solar panels worldwide indirectly shut down during peak sunband.