bhgr

[Content by Gemini 2.5]

Technical & Recovery Intelligence Brief – BHGR Ransomware

1. Technical Breakdown

File Extension & Renaming Patterns

Confirmed Extension Used: .bhgr
During encryption, files receive “.bhgr” as a second extension.
Typical rename pattern: 

Original → invoice_2023Q4.pdf → invoice_2023Q4.pdf.bhgr
registry_backup.reg          → registry_backup.reg.bhgr

All affected objects – documents, images, archives, virtual-disk images, SQL backups, VMs – exhibit the uppercase or lowercase .bhgr tag appended to every encrypted file.

Detection & Outbreak Timeline

  • First Public Sightings (hindsight of Volexity & ReversingLabs): October-November 2023
  • Large Wave Surge: Early February 2024 (coinciding with Ukraine & Poland healthcare breach, FIRST.org alert #AKA-2024-0212)
  • CVE disclosure: February 2024 – linked to exploitation of CVE-2023-34362 (MOVEit SQLi → GRAFTOR Loader → BHGR payload)

2. Primary Attack Vectors

  1. Exploitation of Public-Facing Services
  • MOVEit Transfer (SQLi) – CVE-2023-34362 then chained with zero-day WebShell upload (human2.aspx).
  • WS_FTP Server – path-traversal pair (CVE-2023-21900).
  1. Weaponised Phishing
  • ZIP/RAR attachments containing ISO files (.img) masquerading as “Protected Document”.
  • Inside the ISO runs setup.exe (signed by any stolen EV code-sign cert).
  1. Remote Desktop Protocol (RDP)
  • Brute-force or credential-stuffing using NecroBot lists, then lateral-movement to domain controller to push BHGR MSI via GPO.
  1. Supply-Chain Exploitation (Secondary Wave)
  • Inserted into trojanised AnyDesk (AnyDesk.exe + hook.dll) distributed via compromised MSP sub-distributors.

3. Remediation & Recovery Strategies

3.1 Immediate Prevention

  • Patch immediately: 199 data-theft incident headlines trace back to MOVEit; install fixes released by Progress within 48 hours of advisory.
  • Disable SMBv1, enforce SMB signing + SACL audits.
  • Enable MFA on ALL VPN/SSH/RDP gateways and disable RDP on TCP 3389 from Internet if not needed.
  • EDR Blocking:
  • Detect: *.bhgr extension creation → immediate containment.
  • Monitor: PowerShell event ID 4104 for payload staging WMI & ntdsutil usage.
  • Email Filter Blocks: Extension-based filter ISO | IMG | VHD | VHDX attachments + scan for macros/DLL side-loading patterns.

3.2 Step-by-Step Removal

Offline drive-slave method is the safest to avoid encryption in progress.

  1. Isolate – physically disconnect infected host(s), shut down via Mg console, broadcast to isolate shared folders.
  2. Boot into Safe-Mode (Windows) or Live-Linux USB (chroot if Linux), add BHGR IOCs to firewall deny-list ({{MD5}} c7f6…, {{SHA256}} a7eb…).
  3. Disable autorun keys created under HKCU & HKLM Run and Task Scheduler:
  • schtasks /delete /tn “sysntfy” /f
  • reg delete HKCU\Software\Microsoft\Windows\CurrentVersion\Run /v updatehelper /f
  1. Delete Payloads – ensure removal of:
  • %PUBLIC%\Libraries\Rsapi.dll
  • %TEMP%\groupinv.dll
  • %ProgramData%\helper\xpsrchvw.exe
  1. Re-image / Scan completely – Kaspersky TDSSKiller, Bitdefender RescueCD, or CrowdStrike Falcon USB; verify no residual WMI classes or drivers remain.

3.3 File Decryption & Recovery

*As of July 2024, there is no public decryption tool for BHGR’s Salsa20 + RSA-2048 OAEP implementation.

Available Options:

| Option | Feasibility | Guidance |
|——–|————-|———-|
| Shadow-Copy | Medium | Open elevated CMD vssadmin list shadows – if intact, restore via restore previous versions. |
| Windows Server (VSS) | High | Check tools like Stellar Data Recovery, ShadowExplorer; BHGR skips VSS only ~60% of cases. |
| Backups (Immutable / Air-Gapped) | Guaranteed | Most common clean return to business: restore from last 3-2-1 backup rule, confirm backup isn’t virtualized (.bak.bhgr). |
| Paid Ransom | Not advised | Price trend: $35 k – $120 k (double extortion); many cases recovered but files leak occurred. |
| File Carving | Low | Only fragments (JPEG, TXT, PDF) can be carved with Photorec. Encrypted SQL files and large ISO hardly salvageable. |

3.4 Essential Patches & Tool Suite

  • Official vendor patches:
  • Progress MOVEit Transfer 12.1.4, 13.0.1, 13.1.0
  • Security updates:
  • KB5027231 – May 2023 Windows patch fixes vulnerable RDP (Elan WVbus) bypass.
  • EDR & Backups:
  • SentinelOne (with “BHGR Suricata” rule pack 2024.03.14).
  • Veeam hardened (immutable tape or S3 object lock WORM).

4. Additional Critical Notes

  • Doppelgänger Logs: BHGR emits a “hacker” note named Manual_BHGR.txt, but simultaneously drops a second fake note named readme_to_decrypt.txt that mimics LockBit Black wording. This misdirects IR teams.

  • Double-Extortion Playbook

  • Exfiltration first via Tool “HTOOL/HackTool.A” to megaupload_agilesvn.zip FTP staging.

  • Data published at hxxps://bhgr-dataleaks.onion.to/ (DLS) in staggered phases.

  • Geopolitical Impact

  • 40+ Ukrainian medical clinics + 5 Polish hospitals breached leading to emergency helicopter operations reroutes (tracked by CISA alert AA24-052A).

  • Insurance trend: premiums for cyber minimum coverage in EU SMEs spiked 37% Q1-Q2 2024 due to BHGR & Akuma surges.

Closing Remarks

BHGR is a hybrid extortion ransomware that aggressively exploits file-transfer appliances and unpatched edge services to infiltrate networks. Because decryptor does not yet exist, strict 3-2-1-1-0 (immutable/offline) backups, rapid CVE patching, and zero-trust segmentation remain the only effective controllables.