bi_id

[Content by Gemini 2.5]

Understanding & Combating the BI_ID Ransomware

(Associated with the “.bi_id” file extension)

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Exact file extension added: **.bi_id**
  • Renaming Convention:
    Original filename → <original name>.bi_id
    (e.g., Report_2024.xlsx → Report_2024.xlsx.bi_id).
    The malware usually preserves the original base name and simply appends .bi_id.

2. Detection & Outbreak Timeline

  • First submitted samples: June 2020.
  • Mass-mailing / exploit-kit wave: July–September 2020.
  • Geographic peak: Eastern Europe, rapidly spreading to LATAM & APAC via cracked-software forums.
    (Malware analysts still see scattered activity every few months.)

3. Primary Attack Vectors

| Vector | How it is used (with examples) |
|—|—|
| RDP (Remote Desktop) | Attacks on mis-configured or factory RDP/TCP 3389 ports; brute-force or past-password dumps. |
| EternalBlue/DoublePulsar (SMBv1) | Automated scanners drop the dropper on exposed port TCP 445. |
| Phishing e-mails | Zip attachments “invoice_July.zip → invoice.doc.js” that Base64-decode the payload (winlogon.exe.bi_id.exe). |
| Cracked torrent masquerades | Fake Photoshop, Autodesk, Office activators pushed on warez sites that silently instigate the .bi_id binary.

Remediation & Recovery Strategies:

1. Prevention

  • Patch instantly: Disable SMBv1 (dism /online /disable-feature /featurename:SMB1Protocol) and apply MS17-010.
  • Harden RDP:
    – Move port away from 3389 OR require VPN / SSH tunnel.
    – Enable Network Level Authentication (NLA) & account lockout after 5 failed logons.
  • Phishing firewall: Filter macro MIME types (.js, .vbs, .wsf) in mail gateway.
  • Application whitelisting: Windows Defender Applocker or WDAC “Explicit Allow” mode for %TEMP%.
  • Offline + cloud backups with versioning (e.g., AWS S3 Object Lock, Veeam immutable repos).

2. Removal (Step-by-step)

  1. Isolate host: Pull network cable / disable Wi-Fi.
  2. Boot to Safe Mode with Networking (Windows ≥8: Shift+Restart → Troubleshoot → Startup Settings).
  3. Kill malicious processes:
  • Use RogueKiller, Malwarebytes, or native Event Viewer → App & Service Logs → Microsoft → Windows → WMI-Activity/Operational to spot WMIC launcher.
  • Kill winlogon.exe, mshta.exe instances not in C:\Windows\System32.
  1. Clean registry persistence:
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run → “LibFile” = “%USER%\AppData\winlogon.exe.bi_id.exe” – DELETE.
  • Same under RunOnce, TaskScheduler\\Microsoft< GUID >.
  1. Scan & Quarantine: Run ESET Cleaner or Bitdefender rescue disk then reboot.

3. File Decryption & Recovery

  • Free decryptor? YES – Kaspersky Labs released “RakhniDecryptor 2.2+¹”.
  • Signature match: bi_id → XOR hybrid stream cipher.
  • Prereqs: ORIGINAL (UNencrypted) variant of at least one file present (to retrieve encryption nonce).
  • Process:
  1. Copy a known good copy + encrypted .bi_id file to a USB stick.
  2. Launch RakhniDecryptor.exe → Browse folder → Begin scan.
  • Time estimate: ~1–2 GB/min on SSD for small/medium-sized organizations.
  • Alternative: Shadow Volume Copies: vssadmin list shadows + shadowexplorer if VSS not purged (rare).

4. Other Critical Information

  • Unique characteristics:
    – Leaves bilingual ransom note “ReadMeBI.txt” (EN+RU).
    – Deletes Windows Event Logs (wevtutil cl Security) but DOES NOT wipe shadow copies on Windows 11, enabling partial recovery.
  • Broader impact:
    – Tied to Dharma/CrySiS affiliate program; re-used source code thrives through fresh affiliate packs once public decryptor signatures lag.

¹ Kaspersky RakhniDecryptor download page: https://support.kaspersky.com/viruses/utility#146619279

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