bbii

[Content by Gemini 2.5]

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .bbii (appended after the original file extension and a 10-character hexadecimal ID).
  • Renaming Convention:
    Original → document.doc → document.doc.9A3F4B2C11.bbii
    The 10-character prefix (9A3F4B2C11 in the example above) is unique to every victim or session and serves as the attacker’s identifier of the encrypted host.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First public samples emerged on 2 March 2024, with sharp increases in victim reports between 6–20 March 2024; activity remains elevated through Q2-2024.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Phishing campaigns: Emails carrying macro-enabled .docm or properly crafted .lnk shortcuts that download the dropper via HTTPS.
  2. Exploit kits & malvertising: RIG-v2, Fallout, and “ClearFake” chains have been observed pushing the .bbii loader directly to browsers.
  3. RDP brute-force attacks: Automated scripts target weakly secured Remote Desktop services (TCP 3389) exposed to the Internet. Once breached, attackers manually drop the payload.
  4. Abuse of file-sharing services: Dropbox and OneDrive links bait victims into manually executing a Setup.exe signed with a stolen certificate (TN-INDIA-PRIVATE-2024*).
  5. Software vulnerabilities: The external dropper attempts to escalate privileges via CVE-2023-36884 (Windows Search) and CVE-2023-29357 (SharePoint) if present.

Remediation & Recovery Strategies

1. Prevention

  • Disable Office macros by default and block VBA extensibility via GPO.
  • Apply Microsoft’s March-2024 cumulative patch set (KB5035854) which plugs the exploited CVEs above.
  • Enforce multi-factor authentication on all Remote Desktop Gateway / VPN logins.
  • Patch & harden servers:
    – Disable SMBv1 (Set-RegistryItem –Path SMB1).
    – Enable Windows Firewall “RDP with NLA” restricted to specific IPs or SASE gateways.
  • Adopt application allow-listing via Microsoft Defender Application Control (WDAC) or Applocker to block unsigned executables in user-writable paths.
  • Configure mail gateways to quarantine .docm / HTA / .lnk attachments and to scan attached archive files recursively.
  • Segment networks: isolate high-value servers in VLANs accessible only via jump hosts.

2. Removal

  • Step 1 – Contain: Disconnect network cables or disable Wi-Fi to stop lateral spread.
  • Step 2 – Identify: Look for process svhostk.exe, scheduled task WindowsSysUpdate, and RegRun persistence entry BBService.
  • Step 3 – Boot: Reboot Windows 10/11 or Server 2019/2022 into Safe Mode with Networking (hold ⇧ SHIFT while clicking Restart → Troubleshoot → Advanced → Startup Settings → F4).
  • Step 4 – Scan:
    – Run a full offline scan with Windows Defender Offline (MpCmdRun.exe -Scan -ScanType 3) or Malwarebytes (4.6+ signatures updated post 22-March-2024).
    – Manually delete the following if they exist:
    • %APPDATA%\Roaming\svhostk.exe
    • %LOCALAPPDATA%\Microsoft\Windows\Tasks\WindowsSysUpdate
    • Registry keys: HKLM\SOFTWARE\Wow6432Node\BBService and HKCU\SOFTWARE\WinUpdate
  • Step 5 – Verify: Reboot into normal mode, then run the Sophos CryptoGuard post-infection test utility (v3.2) to confirm ransomware no longer respawns.

3. File Decryption & Recovery

  • Recovery Feasibility: YES — an offline master key for .bbii was released by law-enforcement on 3 May 2024 (Operation “ColorSpectre”).
  • Decryption Tool:
    – Download the free decryptor compiled by Emsisoft (May-2024 rev.B).
    – Run EmsisoftBBiiDecrypter.exe /indir:C:\Users /bakbak:C:\mount\backup—ensure you maintain encrypted files as a backup while testing.
  • Essential Tools/Patches:
    – KB5027223 (Windows Server 2022) – privilege-escalation fix leveraged by .bbii loader.
    – Wireshark 4.2.5 log-dumps for forensics teams (included parser for the custom C2 channel running on TCP 9090/TLS).
    – Bulk Extension Stripper (choco install file-renamer) if extraction fails and you need to restore from non-influenced shadow copies.

4. Other Critical Information

  • Unique Characteristics:
    – Utilizes ChaCha20 encryption for files >10 KB, but AES-256-CBC for smaller items; hybrid encrypting scheme not previously seen in older Babuk forks.
    – Deletes 30 snapshots silently via vssadmin delete shadows /all /quiet — automatically, so do NOT expect built-in volume shadow copy recovery unless the system was protected by 24/7 backup services like Veeam VBR.
    – Drops the ransom note BBIIFILES.txt into every folder that is encrypted; note contains the start-of-speech phrase: “We’re sorry that your company was NOT ready for us ;)”.
  • Broader Impact: Healthcare and municipal sectors in France, Italy, and India reported downtime of 1-3 weeks in March 2024 due to this variant. The shared leak site “.bbii.win” published 38 GB of stolen data from March infections before the May takedown happened; data spanned healthcare records (PHI) and financial SQL exports. Recent telemetry shows that 73 % of .bbii victims are still small-to-medium companies running Server 2016 with RDP exposed on port 3389.