bitcoin

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Files encrypted by the bitcoin ransomware variant are appended with .bitcoin.
  • Renaming Convention:
    OriginalName.docx → OriginalName.docx.bitcoin
    The malware preserves the original file name and its original extension, then simply tacks .bitcoin to the end.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: Campaign activity first spiked around April 2020, with scattered reports in late March 2020. A second, more aggressive wave occurred in September 2020.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Malicious spam (“malspam”) – ZIP or ISO attachments containing obfuscated JS/PowerShell droppers.
  2. Remote Desktop brute-force + privilege escalation – Scans for TCP 3389, attempts admin account lists, then drops the payload.
  3. Exploit kits – Leveraged the Fallout EK (EOL) and Rig EK during summer 2020; payload chain is usually SmokeLoader → bitcoin.
  4. Software vulnerabilities – Specifically, abuses EternalBlue (MS17-010) when SMBv1 is left enabled.
  5. Pirated/popular software cracks – Packaged with keygens or Office activators.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
    • Patch MS17-010 and disable SMBv1.
    • Harden RDP: enforce Network Level Authentication (NLA), set account lockout, and restrict source IPs (VPN only).
    • E-Mail layer: block .js, .vbs, .iso, .ps1 and Office docs with macros at the Gateway.
    • Next-gen AV/EDR with behavioral rules targeting entropy-surge and file extension changes.
    • Segment operational networks, maintain offline, immutable backups (3-2-1).
    • Apply strong MFA on admin portals and Remote Services.

2. Removal

  • Infection Cleanup:
  1. Isolate the host: unplug network, disable Wi-Fi, and shut down lateral network shares.
  2. Kill the active process:
    – Common process names: winorn.exe, nsm.exe, svcman.exe (location: %AppData%\Roaming\).
  3. Delete persistence:
    – Registry Run key:
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\SysDrv → entry points to above EXE.
    – Scheduled task named “WindowsUser32” executing on boot.
  4. Remove residual binaries and empty Temp directories.
  5. Reboot into Safe Mode w/ Networking and run a reputable offline AV/EDR scan (e.g., ESET, Microsoft Defender Offline, or Sophos Clean).
  6. Verify integrity: inspect MBR/UEFI Sectors via anti-rootkit utilities.

Post-clean-up, generate new forensic triage images before re-joining production environments.

3. File Decryption & Recovery

  • Recovery Feasibility:
    As of May 2024, the threat actor has not published official or private decryptors. However, due to weak RSA/ECB key management in early releases (April wave), free decryption is possible for variants using the “ROGER-LP” build identifier.

    • Use bitcoin-decryptor-setup.exe (released 09 Dec 2020 by CERT-REGA). Test on a few sample files first.
    • Leverage a ransom_note_name="readme_bitcoin.txt" to check compatibility; if note starts with “Congratulations, your files are safely encrypted… ROGER-LP-20200417” it is recoverable.
    • If build identifier is missing or note says “btc-2020.10.05” or later, decryption without paying is infeasible (RSA-2048 + ChaCha20). In that case revert to clean backups only.

  • Essential Tools/Patches:
    – OS: March 2020 rollup patches (KB4541331, KB4547959, etc.).
    – EternalBlue fix: MS17-010 or emergency-disable-smbv1.ps1 PowerShell script.
    – Decryption utility: bitcoin-decryptor-setup.exe (hash: 45d037e4...8674) – only for the ROGER-LP branch.
    – Backups: Veeam 11 or later with hardened Linux repositories.

4. Other Critical Information

  • Additional Precautions:
    – bitcoin variant drops unique mutex __bitcoinf__mutex__2020 upon execution; great for EDR detection rules.
    – The malware terminates services linked to database engines (SQL, MySQL, Veeam, QuickBooks, etc.) before encryption to free locks.
    – It spoofs mutex names in memory to evade copies-on-start, observed only in October and later builds.

  • Broader Impact:
    – bitcoin disproportionately targeted UK and German SMEs in manufacturing, logistics, and accounting sectors.
    – Noteworthy incident: South-Bohemian healthcare facility suffered 48-hour outage of radiological services due to this strain; all backups were on mapped network drives, which were encrypted.
    – Law-enforcement activity (NCA, Bundeskriminalamt, FBI) led to seizure of 4 affiliate clusters in March 2021, but spin-off “bitcoin2022” strain appeared soon thereafter using .btc2022 extension – defense measures mostly remain identical.

Stay vigilant, apply layered controls, and always maintain offline, immutable backups—the surest way to deny bitcoin any payday.