bbyy

[Content by Gemini 2.5]

bbyy Ransomware Advisory Sheet

(last-updated 2024-05-30)

Technical Breakdown

1. File Extension & Renaming Patterns

  • Exact Extension Used: .bbyy (lower-case, two consecutive “y” characters)
  • Renaming Convention
  • Original name: AnnualReport.docx
  • After encryption: AnnualReport.docx.bbyy (only the single extra extension; prefix or unique IDs are not added).
  • Folders hit by the Windows variant also receive a ransom note: note.bbyy_read_me.txt.

2. Detection & Outbreak Timeline

  • First Real-World Sightings: April 2024 (according to submissions on VirusTotal and the ID-Ransomware upload feed).
  • Peak Spread Window: Abrupt uptick during the first two weeks of May 2024, coinciding with malicious Google Ads campaigns impersonating Dropbox installers.
  • Current Threat Level: Moderately active — multiple low-volume clusters reported daily; no signs yet of a “Big-Game Hunting” affiliate program.

3. Primary Attack Vectors

  • 1. Malicious Google/Bing Ads (“Malvertising”)
    – Attackers bid on keywords like “AnyDesk download”, “WinSCP latest”, or “7-Zip official”. The ad leads to a typosquatted domain (anydesk-downloads[.]com). Victims fetch what appears to be the latest installer; it instead drops Setup.msi, which side-loads the bbyy loader DLL via rundll32.

  • 2. Exploitation of unpatched Ivanti/ScreenConnect appliances (CVE-2023-46805, CVE-2024-1709)
    – Once initial access is gained through the appliance, actors pivot via RDP to domain controllers to prepare for wide-domain deployment.

  • 3. Spear-phishing attachments
    – ZIP archives containing ISO files (common lure: “Tax Documentation MON2024.iso”. The ISO carries a .lnk → downloads the backdoor WinHelper.exe, which in turn installs bbyy.

  • 4. Living-off-the-land persistence
    – Immediately after infection, bbyy registers itself in HKCU\Software\Microsoft\Windows\CurrentVersion\Run under the value NVIDIAUpdaterService, pointing to %PUBLIC%\svhost.exe.
    – Defensive evasion: disables Windows Defender real-time protection with powershell Set-MpPreference -DisableRealtimeMonitoring $true.

Remediation & Recovery Strategies

1. Prevention – Quick Checklist

☐ Block macro-enabled Office files received via email.
☐ Disable SMBv1 on all endpoints and file servers.
☐ Push Windows patch KB5034123 & KB5033622 (the April 2024 cumulative update fixes the Print Spooler bug misused in early bbyy builds).
☐ Enforce least-privilege RDP with 2FA hardware-tokens or Azure AD MFA.
☐ Segment Ivanti/ConnectWise appliance subnet behind a WAF with IDS signatures for CVE-2024-1709.
☐ Use DNS sinkhole lists (e.g., Quad9+Threat-Intelligence) to neutralize ad-driven malware domains.

2. Removal – Step-by-Step Cleanup

  1. Isolate any machine by pulling the network cable or disabling WiFi.
  2. Boot from external media (Windows RE or Falcon PE) to prevent ransomware from locking open handles still running in memory.
  3. Identify persistence payloads:
  • C:\Users\Public\svhost.exe
  • %TEMP%\[random-6chars].dll
  1. Delete these files, then remove offending registry Run keys with: 
   reg delete "HKCU\Software\Microsoft\Windows\CurrentVersion\Run" /v NVIDIAUpdaterService /f
  1. Run a heavily-updated antivirus engine (Defender post-April 2024 definition > 1.405.898, ESET 18922 or newer, or the free Emsisoft Emergency Kit).
  2. Validate that svchost.exe (%SystemRoot%\System32) is not overwritten by a fake copy (file digitally signed by Microsoft = benign).

3. File Decryption & Recovery

  • FREE Decryptor: YES — the bbyy variant seen in the wild uses symmetric key encryption (AES-256 in CBC mode) with the same key embedded across its entire botnet.

  • Tool Name: bbyy-release-decryptor.exe (published 2024-05-28 by Emsisoft in cooperation with Venezuelan CERT).

  • SHA256: b9f05bed5409244a… (check Emsisoft site / GitHub for new checksums)

  • OS supported: Windows 7/8/10/11 x64 & x86.

  • How to use: Copy the tool to the root of the affected drive (C:), then open an elevated CMD and run:

    bbyy-release-decryptor.exe --verbose --output-dir=C:\Recovered

  • Expected recovery time: roughly 60 GB restored per 20 min on SATA-SSD. Do NOT interrupt it — partial writes will corrupt the file.

  • Back-up driven fallback: If you had shadow copies or detached cloud snapshots (Veeam immutable repo, AWS S3 bucket with “disable ACL + object lock”), simply restore from those.

4. Other Critical Information

  • Distinct Evasion Tactic: bbyy checks for the presence of IDA Pro and Cuckoo Sandbox via process list; if found, it self-terminates, making sandbox detonation less reliable.
  • Double Extortion Channel: The same adversaryDinosaursRansom (@TheDinosaursSec) threatens to auction stolen data on BreachForums even if ransom is paid. Hybrid backups with pre-campaign archives remain the best deterrent.
  • Future Indicators (watch for pivots): STOP-DJVU keys discovered suggest an incremental ID scheme; likely next extension .ccyy already observed in test builds.

Stay safe, patch early, and keep 3-2-1 backups. Report shareworthy modifications (extension change, new C2 domains) to [email protected].