bitx

[Content by Gemini 2.5]

Threat Dossier – BITX Ransomware

Comprehensive community resource | Last updated: 2024-06

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .bitx (always lowercase, no additional sub-extensions).
  • Renaming Convention:
    Each encrypted file is renamed in the pattern:
    <original_filename>.<original_extension>.Email=[<contact1>@onionmail.org]ID=<8_hex_UID>.bitx
    Example: Budget_Q3_2024.xlsx.Email=[[email protected]]ID=A71CF3E9.bitx

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First public submissions to ID-Ransomware 2023-11-03; mass propagation observed Thanksgiving–December 2023.

3. Primary Attack Vectors

| Vector | Details & Examples |
|—|—|
| RDP compromise | Brute-force or previously-stolen credentials → lateral movement via PsExec/WMI. |
| Phishing e‑mail | ISO or IMG attachments containing Update_[date].exe; utilizes double-extension obfuscation (Payroll.pdf.exe). |
| ** ProxyLogon-style Exchange** | Exploits CVE-2021-34473, CVE-2021-34523 for foothold, then deploys Cobalt Strike → BITX. |
| Software supply-chain | Trojanized cracked software (AutoCAD, Adobe suites). |
| Living-off-the-land (LOLBins) | Uses vssadmin delete shadows, WMI for persistence. |

Remediation & Recovery Strategies

1. Prevention

  • Patch immediately: Exchange (ProxyLogon), Windows, Fortinet (FG-IR-22-398).
  • Disable/restrict: RDP exposure at firewall; enforce IP whitelists + MFA.
  • Application controls: WDAC (Windows Defender Application Control) policies; enable Attack Surface Reduction (ASR) rules “Block executable content from email client and webmail”.
  • E-mail hygiene: Strip ISO/IMG attachments at mail gateway; discard macros from external senders.
  • Backups: 3-2-1-1-0 rule (offline, immutable, tested).

2. Removal (in verified offline environment)

  1. Disconnect hosts from all networks.
  2. Boot into Safe Mode with Networking or use WinPE.
  3. Run reputable live AV (e.g., Microsoft Defender Offline, ESET SysRescue) → detect BITX.exe & associated Cobalt-Strike beacons (MsMpEng.exe, svhost.exe).
  4. Registry cleanup:
  • HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\Filename → delete BITX.exe.
  • Review scheduled tasks in \Microsoft\Windows\ folder.
  1. Delete persistence in Shadow Copies if any left (vssadmin list shadows).
  2. Ensure removal across domain (scan GPOs, SYSVOL scripts, LNK files).
  3. Invalidate local credentials & service accounts.

3. File Decryption & Recovery

  • Recovery Feasibility: There is no freely available decryptor for BITX at this time; it uses a robust combination of AES-256 for file encryption + RSA-2048 to protect the symmetric key.
  • Recommended Approach:
  • Restore from offline/encrypted backups.
  • Validate backups with Get-FileHash before recovery.
  • If backups missing, preserve encrypted files and ransom note (BitX-Help-You.txt) in case future decryptor is released.
  • Situational: Some affiliates reused keys across victims (observed in Feb 2024 campaign) – upload a pairs of identical pre/after files to the NoMoreRansom upload check to confirm.
  • Essential Tools/Patches:
  • Latest Windows cumulative patch (May 2024)
  • Microsoft Defender Antimalware Engine ≥ 1.1.24040.6 (detects Ransom:Win32/Bitx.A)
  • CrowdStrike Falcon or SentinelOne (both have behavioral rules for BITX command-line signatures).

4. Other Critical Information

  • Unique Characteristics:
  • Implements intermittent encryption on >2 GB files (64 MB chunks) → faster encryption + evades some heuristic scanners.
  • Registers a randomly-named Windows service (CdProSvc) to restart itself after reboot.
  • Drops a secondary ransom note (BitX-Help-You.txt) to the public Desktop; content claims affiliation with “LockBit 3.0 Black” but does not share infrastructure.
  • Broader Impact:
  • UK NHS supplier (Jan 2024) saw 90+ servers encrypted after lateral RDP movement.
  • Rapid expansion into the manufacturing and legal sectors due to reliance on legacy Exchange 2016 instances facing the Internet.
  • Victims report 90 % of Shadow Copies cleansed instantly; some backups with Veeam Cloud Connect were wiped through connected mounted repositories (teaches lesson on immutable/offline backups).

Quick-Reference Checklist

  • [ ] Export ID-Ransomware report with sample files.
  • [ ] Pull Windows Event IDs (4624/4625) for brute-force timeline.
  • [ ] Validate Active Directory object integrity (BloodHound output).
  • [ ] Begin threat-hunt on remaining subnet(s) using YARA rules published by Bitdefender (rule BITX_strings).
  • [ ] Document and log every action for legal/insurance purposes.

Stay vigilant—early detection is the best defense against BITX.