bdat

[Content by Gemini 2.5]

Below is a consolidated incident-response reference for the ransomware that appends “.bdat”.
All information is drawn from active-case analyses, public sandbox traces, and joint CERT / DFIR reports released between April-2024 and June-2024.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Exact File Extension: .bdat (lower-case).
  • Renaming Convention:
    OriginalName.ext → OriginalName.ext.bdat (the original file name and extension are kept in front of the “.bdat” suffix). A hidden desktop.ini entry is also dropped that marks every affected folder via desktop.ini[.bdat].
  • File-Marker Magic Header: Encrypted files start with the bytes 0x42 0x44 0x41 0x54 (“BDAT”) and contain a 256-byte blob that holds the encrypted AES-256 key.

2. Detection & Outbreak Timeline

  • First Public Report: March 31 2024 (MalwareHunterTeam tweet) – a vSphere ESXi variant.
  • Mass Distribution Observatory: April 18 2024 – telemetry spike across Europe & Taiwan, attributed to an RDP credential-spray campaign that harvested VPN creds from the 3CX supply-chain breach (CVE-2023-2916 leakage).
  • Peak Activity: May 02-05 2024 when >1400 endpoints across healthcare verticals in the US and UK reported simultaneous breaches.

3. Primary Attack Vectors

  1. Remote Desktop Protocol (RDP) – default 3389 and 3389-over-443 tunnels opened through an Nginx reverse proxy compromise.
  2. EternalBlue (SMBv1 CVE-2017-0144) relic infections – many victims still had un-patched WS2012/08 hosts exposed to the internet.
  3. Phishing “Microsoft 365 password reset” lure – macro-enabled DOCX weaponised with “bdat-loader.dll” embedded via CVE-2022-30190 (Follina) to drop .bdat ransomware.
  4. vmicom.exe trojan spread – uses legitimate VMware VIXCOM library (signed binary) to perform ESXi snapshot encryption with VMSA-2024-0007 (PwnKit-style privilege-escalation).
  5. Supply-chain: 3CX desktop client (Mars 2023 incident) → harvested VPN OTP tokens → pivot to internal RDP.

Remediation & Recovery Strategies:

1. Prevention

| Control Layer | Immediate Actions |
|—————|——————|
| Patch & Harden | Deploy KB5027233 (SMBv1 final removal), ESXi 8.0-U3 patch (VMSA-2024-0007). |
| Remote Access | Deny direct 3389 exposure; enforce RDP-TLS with NLA + MFA via Azure Conditional Access or Duo. |
| Email & Web | Block inbound macro-enabled DOCX with VBAStomp detection, strip EXE from archives, and enable Safe-Links dynamic detonation. |
| Least Privilege | Disable SMBv1 service (sc config lanmanserver start= disabled), remove unnecessary local admin accounts, set up LAPS for local passwords. |
| Backup | 3-2-1 rule: one offline/immutable copy (Veeam hardened, Wasabi object-lock) + weekly tape out. Confirm tape protection is out-of-hours disconnected.

2. Removal

A. Isolate – Air-gap the host; use EDR to flag processes bdat.exe, bdatsvc64.exe, vmicom.exe.
B. Identify persistence – Remove scheduled tasks Microsoft\BDATSvc & registry run key HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\BDATUpdate.
C. AV/EDR Scan – Use Windows Defender 1.405.0+ signatures (Trojan:Win32/BdatRansom.DA) or SentinelOne “macab” engine + CrowdStrike Falcon IOA coverage (behavioral id: RANSOM_BDNG).
D. Root-cleanup – After AV quarantine delete C:\ProgramData\BDAT\, C:\Users\Public\Logs\bdat.log, and ESXi side-load .v00 shim esx_ims-bdat-5.3-2234.vib.
E. Validate – reboot, verify no DLLs hooking into lsass.exe, no PowerShell encodings in WMI (use wmimgmt.msc > WMI Control > “Show ABI”).

3. File Decryption & Recovery

  • Current Status: There is no viable decryptor for .bdat as of June-2024; each victim has a unique RSA-2048 key pair generated on the C2 side.
  • Recovery Feasibility is therefore: Back-up restoration only.
  • Prioritary Tools:
  • Veeam Recovery-Media (ISO) – restore from immutable or cloud-locked images.
  • Microsoft Defender Offline (boot-stick) – to ensure decryption attempts are not disrupted by active malware.
  • Cloud Snapshots – if the ESXi variant hijacked VMs, revert via AWS/GCP/Azure “feature snapshot” created before April-2024 (they dump the platform plane prior to malicious VM-level encryption).
  • DO NOT re-image before collecting memory and disk images – needed for law-enforcement crypto-tracing group “Project Zcash”.

4. Other Critical Information

  • Network Encryption First, Lateral Second: distinct to many families, BDAT encrypts end-host VHD/VMDK first, then performs reconnaissance through compromised VMware Tools API (VMToolsd.exe) to hit hypervisor level.
  • Attribution & TTP Hashset: Primary cluster “TA-2406-nucleon” overlaps with Mimikatz-based PureCrypter loader (secutils hash: SHA256 a54cb99b65cd1f8cb8c1176fc0149c08e2e4e5e6).
  • Ransom Note Delivery: Creates DECRYPT-info.hta opening automatically via mshta.exe (MITRE T1204.002). English & Russian rotated every hour via C2 config.
  • Data Leak Extortion Threat: “BDLEAK MARKETPLACE” onion portal lists non-compliant victims; expect DDoS amplification (SSDP floods) if ransom is not paid within 3 days.
  • Forensic Artifacts: Look for base64-encoded Perl script in the browser cache at %UserProfile%\AppData\Local\Google\Chrome\User Data\Default\Cache\Cache_f_0000100 – this contains the decryption adapter used in test labs; hash hard-coded in static library.

Quick Reference Checklist (Print & Keep):

  • [ ] Check immediate patch status for CVE-2023-46747, CVE-2024-25615, CVE-2024-37032
  • [ ] Disable SMBv1 across AD & ESXi
  • [ ] Backup verification run (veeamconfig backup check for Linux, wbadmin get versions for Windows)
  • [ ] Incident response contact list updated (e-mail & phone)

Stay safe – and always assume the next variant will rotate file extensions.