bboo

[Content by Gemini 2.5]

bboo Ransomware – Technical & Recovery Handbook

Ransomware ID: STOP/DJVU variant with .bboo extension

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: All encrypted files receive the second-level extension “.bboo” (for example, invoice.xlsx.bboo or 1.jpg.bboo).
  • Renaming Convention: Files keep their original name and first extension, then the malware appends “.bboo” without altering any prior characters or directories.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: The “.bboo” strain first surfaced in late January 2020, with peak distribution waves continuing through February–March 2020 and periodic resurgences ever since. Microsoft Defender and several AV engines added signatures in early February 2020.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Malicious e-mail attachments (fake invoices, software updates, or purchase confirmations) containing macro-laden MS Office files or executables camouflaged as PDF/ISO archives.
  2. Compromised “warez” / torrent distributions of pirated software (Adobe, game cracks, keygens).
  3. Drive-by downloads from exploit kits (most commonly RIG, Fallout, and SmokeLoader).
  4. Exploitation of weak (brute-forced) Remote Desktop (RDP) passwords, then lateral movement via SMBv1 (NBT-NS poisoning or EternalBlue-like abuse when available).
  5. Secondary payloads delivered by existing infections (TrickBot, SmokeLoader, Amadey botnets).

Remediation & Recovery Strategies

1. Prevention

  • Proactive Measures:
    • Patch Windows (especially SMBv1, RDP, MS17-010) and Java/Acrobat/Office applications aggressively.
    • Disable PowerShell 2.0 and script-based execution policies if not essential.
    • Deploy Microsoft Defender with Real-time + Cloud-delivered protection, or a reputable EDR/NG AV stack (preferably with “block at first sight” and network protection).
    • Adopt a least-privilege policy: remove administrative rights from end-users and restrict RDP access to specific IP ranges with enforced MFA.
    • Maintain 3-2-1 backups – three copies, on two media, at least one off-site/off-line and regularly tested.
    • Enable Windows Controlled-Folder Access (CFA) to limit third-party encryption attempts.
    • Filter e-mails for macro attachments, ISO archives in ZIP bundles, and IOC domains noted below.
    • Disable default “.hta,” “.js,” and “.vbs” file handlers in Windows if not needed.

2. Removal

  • Infection Cleanup (Step-by-Step):
  1. Immediately disconnect the affected machine(s) from the network (wireless and Ethernet).
  2. Boot into Safe Mode with Networking.
  3. Run an up-to-date AV scan (Microsoft Defender Offline, ESET Online Scanner, or Malwarebytes) to quarantine the following known binaries:
    • %AppData%\{random}\system.exe
    • %Temp%\updatewin.exe
    • {random}.exe in the same folder that created the readme.bboo.txt ransom note.
  4. Inspect Task Scheduler and Registry Run keys (HKCU\Software\Microsoft\Windows\CurrentVersion\Run) for the same names; delete malicious entries.
  5. Restart and confirm no malicious process shows in Task Manager; verify no new *.bboo files are created on test data.
  6. Reset local and domain credentials that were logged in at the time of infection.

3. File Decryption & Recovery

  • Recovery Feasibility:
  • Offline-key infections (when the malware fails to reach its command-and-control or uses hard-coded keys): decryptable for free.
  • Online-key infections (servers retrieved a unique RSA key per victim): not decryptable without paying ransom—yet you can usually recover versions via backups, cloud snapshots, or shadow copies.
  • Essential Tools:
  • Emsisoft STOP-DJVU Decrypter v1.0.0.17 (or newer) – detects your key → gives “decryptable” verdict and decrypts if offline key exists (~95 % of v2416, 4/2024 variant). Download from: https://emsisoft.com/ransomware-decryption-tools/stop-djvu.
  • ShadowExplorer or Windows’ built-in vssadmin list shadows – recover previous versions if ransomware failed to delete shadow copies.
  • Recuva / PhotoRec – last-ditch search for remnants of deleted originals.
  • Microsoft 365 / OneDrive / Google Drive restore points – via right-click “Restore previous versions” (undo ransomware changes).

4. Other Critical Information

  • Unique Characteristics:
  • bboo belongs to the STOP/DJVU ransomware family, which is distinguished by embedding a malware ID (“t1” at offset 0x1E of the ransom note) and using Salsa20 encryption + RSA-1024.
  • Decryptor also drops the note readme.bboo.txt and often bundles second-stage malware like Azorult (info-stealer).
  • The malware purposely avoids directories that include Windows, boot, or AV vendor names to preserve OS bootability (so victims can read the ransom message).
  • Broader Impact & Notable Effects:
  • Since January 2020, >700k STOP/DJVU strains have been reported; bboo campaigns have disproportionately hit home users, small/medium CAD/engineering firms, and individual gamers downloading pirated software.
  • The leakage bank-credential module (Azorult) has caused downstream credential-stuffing attacks and Dark-Web listings even after ransom issues were resolved.

Vigilance Checklist (Print & Keep Handy)

[ ] Offline backups verified weekly
[ ] Windows and Office updated yesterday
[ ] MFA on RDP / VPN gateway
[ ] Group Policy blocks execution of EXE in %AppData%**.exe
[ ] Emsisoft STOP-DJVU decryptor bookmarked
[ ] Incident-response runbook taped to sysadmin desk

Stay secure, stay calm, and do not pay if you have backups or the decryptor confirms offline mode—the cybercriminals’ revenue only reinforces the cycle.