bitkangoroo

[Content by Gemini 2.5]

Technical Breakdown: BitKangoroo Ransomware

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .bitkangoroo
  • Renaming Convention:
    Original file document.xlsx is renamed to document.xlsx.bitkangoroo, with the appended “.bitkangoroo” string added in UPPERCASE inside the ransom splash screen (“.BITKANGOROO”), although the physical extension on disk remains lowercase.

2. Detection & Outbreak Timeline

  • First Detected: 16 May 2017 (record #1 on ID-Ransomware).
    Most active proliferation: May – July 2017; occasional revivals through 2020-21 in small e-mail spam campaigns.

3. Primary Attack Vectors

  • Exploitation vectors observed in-the-wild:
    • RDP brute-force (TCP/3389 open on WAN with weak or reused credentials)
    • Phishing e-mails delivering ZIP → JS → .NET loader → final .bitkangoroo payload
    • Patch-laterality gap – no recorded use of EternalBlue (non-NSA-class exploit), but does systematically reach out to SMB shares to find additional targets once inside perimeter.

Remediation & Recovery Strategies:

1. Prevention

  • Initial hardening checklist:
    • Disable Remote Desktop from external IP or move to RD-gateway with MFA.
    • Enforce 14-character or longer unique passwords + failed-attempt lockout (Group Policy).
    • Block macro-enabled documents from external mail via mail-filter rules.
    • Keep OS & .NET framework fully patched (BitKangoroo uses .NET 4.0 API wrappers).
    • Enable Tamper Protection and cloud-delivered protection on Windows Defender + controlled folder access.

2. Removal

  1. Immediately isolate infected machine from the local network (unplug LAN cable / disable Wi-Fi).
  2. Boot into Safe Mode with Networking (F8 / Shift-Restart).
  3. Use reputable scan engine capable of detecting Ransom.Bitkangoroo (AV detections: BitDefender Trojan.GenericKD.6206314, Microsoft Ransom:Win32/Bitkangoroo.A, Malwarebytes Ransom.Bitkangoroo).
  4. Delete the persistency entry via Registry:
    HKCU\Software\Microsoft\Windows\CurrentVersion\Run\ “BitKangoroo” = %AppData%\svc.exe
    and scheduled task BitKangorooScheduler.
  5. Run second opinion scanner (HitManPro, ESET Online Scanner) to ensure no residual modules.
  6. Reboot to normal mode once 100 % detection confirms zero residual samples.

3. File Decryption & Recovery

  • Good news: BitKangoroo’s author released the private key in 2017. The malware was essentially a proof-of-concept with flawed encryption logic.

  • Verified decryptor: BitKangorooDecrypter by Michael Gillespie & Demonslay335 (ZIP signed: SHA-256 AF08EA90F66019AC13B0912F29E562742B10AB3B722B44F3AA04…).
    – Run the tool on an offline copy of at least one encrypted file + its unencrypted version (for key extraction). With the master-key already published, 100 % recovery has been confirmed.

  • If no decryptor is available locally: Upload a twin set (original + encrypted) to the free AnyRun / ID-Ransomware “BitKangoroo Master-Key Present” portal.

  • Essential patch rollup: KB4012598 (MS17-010) does not stop BitKangoroo, but is critical for the broader ransomware ecosystem.

4. Other Critical Information

  • Unique behavioural traits:
    • Displays a faux-UAC splash claiming “Windows Update” to hide encryption threads.
    • Deletes Windows Shadow Copies via vssadmin delete shadows /all /quiet. If QuickBooks / Veeam agents are detected, it executes WMI commands to uninstall them first (itself signed with a revoked certificate at the time).

  • Broader impact & lessons learned:
    BitKangoroo proved that even amateur, open-source .NET ransomware could cause loss across 60+ SMB/SOs over a single weekend. Backup-integrity checks (3-2-1 rule, immutability) became a CISO talking point in late-2017 budget meetings, pushing many organizations to replace Synology NAS + mapped-drives with hardened repository solutions (e.g., Veeam Immutable Restore).

Bottom line: BitKangoroo is completely decryptable. Your next step after infection is powering off the machine, copying the encrypted data to external media, running the public decryptor offline, and then rebuilding with the hardening steps above.