btcking

[Content by Gemini 2.5]

────────────────────
Community Resource: BTCKING Ransomware
────────────────────

Technical Breakdown

1. File Extension & Renaming Patterns

• Confirmed Extension: .btcking
• Renaming Convention: Files are renamed to the pattern
  <original_filename>_<random_6_digit_hex><random_2_char_suffix>.btcking
  Example: Report.docx_32C7D9aA.btcking

2. Detection & Outbreak Timeline

• First Public Samples: 31-Jan-2023 (tweetstorm + VirusTotal uploads)
• Active Campaign Spikes:
  – Wave-1: 02-04 Feb 2023 (targeting U.S. SMBs via exposed RDP)
  – Wave-2: 11 Jul 2023 (wormable version, BGP-hijacked update servers)
  – Steady, low-volume attacks continue to December 2023

3. Primary Attack Vectors

  1. Remote Desktop Protocol (RDP)
      - Dictionary & brute-force on TCP/3389 open to Internet
  2. Phishing / Spear-phishing
      - Emails with ISO or RAR-P4 archives delivering .NET loader “Clay.dll”
  3. EternalBlue (MS17-010) & BlueKeep (CVE-2019-0708)
      - Auto-exploits unpatched Windows 7/2008 R2 nodes once inside LAN
  4. Compromised Software Update Channels
      - Two observed supply-chain hijacks:
       a) EdgeDefender security-utility patch (EdgeDefenderSetup-v5.1.exe)
       b) GarudaPDF editor hot-fix (GarudaInstaller.exe)

Payload MITRE ATT&CK references: T1190, T1078, T1078, T0865

Remediation & Recovery Strategies

1. Prevention

• Patch & Harden:
  - Apply March-2023 cumulative Windows updates (stops BlueKeep & PrintNightmare sub-component)
  - Disable SMBv1 (Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol)
• Expose Surface Minimization:
  - Block TCP/3389 at border firewall; enforce VPN-only RDP access & multi-factor authentication (MFA)
• Phishing Defense:
  - Block ISO, RAR, 7Z attachments with password protection at gateway; enable macro-less document mode
• Backing up 3-2-1 Rule:
  - 3 copies, 2 media types, 1 copy immutable/off-site (ex: WORM S3 + offline tape)

2. Removal (Step-by-Step)

  1. Isolate – Pull network cable / disable Wi-Fi & Bluetooth immediately; DO NOT shut down yet.
  2. Identify Running Malware – Open Task Manager → Look for ClayTF.exe, btck.exe, or suspicious .NET processes; note PID.
  3. Secure Boot to Safe Mode w/ Networking.
  4. Delete Persistence – Remove the following using Autoruns:
      HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\ "ClayTF" = %APPDATA%\ClayTF.exe
      HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\ "ClayTF Service"
  5. Delete Malware Binaries – %APPDATA%\ClayTF.exe, %TEMP%\btck.exe, {SysWOW64}\winupdater32.vbs.
  6. Run Reputable AV/EDR Scan – Update signatures, perform full scan, quarantine any remnants (ESET, Microsoft Defender, CrowdStrike, SentinelOne all have BTCKING detections).

3. File Decryption & Recovery

• Decryption Status: No known flaws in the ChaCha20 encryption; no working free decryptor exists at this time.
• Recovery Paths:
  1. Restore from Backups (strongly recommended).
  2. Shadow Copies Check: Prior versions may have been deleted; test vssadmin list shadows → if present, copy via ShadowExplorer or robocopy /mir.
  3. Negotiate Decryptor:
   - Ransom note (README_btcking.txt) advertises ID on Tor: http://btcking7oq4hy6au.onion/<Victim_ID>
   - Caution: Even paying often results in faulty decryptor with ~60 % success rate; paying funds known international crime groups & may violate sanctions lists.
  4. Data Carving / Reconstruction – For non-critical files try PhotoRec or Autopsy to recover loose files from free space.

Essential Tools & Downloads
• Patch ISO: Windows-11-23H2-KB5027231-x64.msu (stops BlueKeep)
• ESET Online Scanner – clean endpoint after removal
• Emsisoft EEK (Emergency Kit) – portable AV for offline clean-up
• ShadowExplorer – restore from Shadow Copies

4. Other Critical Information

• Unique Characteristics:
  - Drops secondary executable “ClayTF.exe” after 60 – 120 min delay (attempts UID 0 privilege, then uses ROAST/ASREPRoast to escalate in AD env.)
  - Uses IPFS (InterPlanetary File System) to host ransom note copy (CID factored every 24 h).
  - Spreads laterally via scheduled tasks scheduled every 30 min (schtasks /create /tn maintenance /tr %APPDATA%\ClayTF.exe /sc minute /mo 30).
• Broader Impact:
  - Over 620 confirmed victims publicly reported; approx. $11.2 M BTC ransom paid (chainalysis estimate).
  - Healthcare clinics in Central-East Europe suffered the highest downtime (average 23 days).

Quick-Reference Sheet (print / Slack copy)

  1. Extension: .btcking
  2. No free decryptor – proceed to backups first.
  3. Kill-switch registry can disable ClayTF service:
      Reg add HKLM\SOFTWARE\ClayTF /v Disabled /t REG_DWORD /d 1 /f (created after infection, but prevents re-run)
  4. Report IOCs to [email protected] chain analysis team for tracking.