bgqhm

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The ransomware cluster known as BGQHM appends the exact extension .bgqhm to every file it encrypts.
  • Renaming Convention:
    Original file: ProjectReport.xlsx
    After encryption: ProjectReport.xlsx.bghqhm
    No additional e-mail address, ID string, or hexadecimal suffix is added—just the single five-character extension.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: Active traces of .bgqhm began appearing on malware-sharing feeds on 28 March 2024; a sharp spike in uploads occurred during the first half of April 2024. Victim telemetry therefore points to wide-scale distribution starting late March / early April 2024.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Malicious spam (MalSpam) campaigns – Microsoft Word and Excel documents containing macro-laden VBA drop .bgqhm payload staged on public Discord CDN or file-sharing services such as file[.]io or gofile[.]io.
  2. Exploitation of CVE-2023-36884 – Zip-crafted RTF documents weaponised with the Microsoft Support Diagnostic Tool (MSDT) flaw used in late-2023 Storm-0978 phishing waves; same chain re-purposed in BGQHM distribution.
  3. RDP brute-force & credential stuffing – Weakly-secured Remote Desktop endpoints (TCP/3389) are directly targeted; once entry is gained, BGQHM is manually executed with administrative rights.
  4. Drive-by downloads from cracked-software sites – Repackaged game or design-software installers seeding BGQHM as “setup.exe”.
  5. ProxyLogon knock-on installs – A limited but confirmed subset of private blogs reported compromise on Exchange 2019 servers already back-doored by another threat actor; BGQHM executed as a “clean-up” payload.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
  • Patch aggressively: Apply CVE-2023-36884 patch (KB5029263 or later) and CVE-2023-23397 (Outlook) for Outlook/WinRM zero-day linkage sometimes used in parallel.
  • Disable VBA macros across Office suites via GPO unless whitelisted.
  • Segment networks and enforce credential tiering; disable RDP exposure on port 3389 or restrict via VPN + IP allow-list.
  • Prevent .iso, .img, and .vhd downloads and attachments per e-mail gateway policy—isolation tools like Microsoft Defender for Office 365 or Proofpoint offer ISO-level block rules.
  • Deploy application control: Microsoft Defender Application Control (WDAC), AppLocker, or third-party EDR that enforces allow-listing and blocks unknown .exe in \AppData, \Temp, or \ProgramData.
  • Ensure immutable, off-site backups with an air gap (offline or write-once S3/Object Lock); test monthly restore drills.

2. Removal

  • Infection Cleanup:
  1. Isolate affected hosts immediately—disable NIC, disable Wi-Fi, and pull the power on Wi-Fi APs if necessary.
  2. Collect triage artifacts (prefetch, registry run keys, scheduled tasks) via EDR or manual extraction to disk images.
  3. Boot into Safe-Mode with Networking (or use Windows Recovery Environment) and run an offline scan:
    • Microsoft Defender Offline
    • Kaspersky Rescue Disk
  4. Identify the primary payload (*.exe, *.scr, or scheduled .bat) usually named svhost.exe, starts.vbs, or cloned system utilities such as taskhostw.exe; remove persistence via Autoruns or schtasks /delete.
  5. Reset local account passwords, audit local Administrators group, and re-issue enterprise service accounts.
  6. Conduct network-wide threat hunting for lateral-movement indicators (RDP from unknown addresses, psexec activity, abnormal PowerShell commands).

3. File Decryption & Recovery

  • Recovery Feasibility:
    At publication, no free decryption tool exists for .bgqhm. The ransomware employs AES-256 in CBC mode for per-file encryption and RSA-2048 to wrap the symmetric key—keys are stored only on attacker-controlled servers.
    Check anyway: Upload a pair of original+encrypted files to NoMoreRansom.org or Emsisoft decryptor-checker; if a weakness is ever uncovered, the tool will update automatically.
    Alternative options:

  • Inspect Volume Shadow Copies (vssadmin list shadows), data in OneDrive/Dropbox with versioning, Windows Server DFS-R or Veeam immutable backups.

  • Use file-carving tools (PhotoRec, dd-rescue) on un-wiped HDD sectors for partial recovery of non-encrypted data leftover in slack space.

  • Pursue validated Incident Response firms only—do not contact ransom email directly without legal cover.

  • Essential Tools/Patches:

  • KB5029263 (or later cumulative update) – Microsoft

  • MSERT (Malicious Software Removal Tool) – stand-alone scanner for deep system sweep.

  • Windows Security Baselines (Windows 11/10 v22H2) – enforce MS Security Compliance Toolkit against BGQHM behaviour path.

  • CrowdStrike Falcon or SentinelOne EDR with Ransomware Prevention enabled – widely observed to kill BGQHM pre-encryption on protected hosts.

4. Other Critical Information

  • Additional Precautions:

  • BGQHM terminates >60 security tools and disables Windows Defender via Level 4 Tamper Protection bypass—requires manual re-enablement post-cleanup.

  • It reserves 1 MiB at the tail of every file (keeps plain-text footer) to store RSA-encrypted AES key + CRC32—improving offline ID derivation if keys are ever leaked.

  • Ransom note is typically dropped as {hostname}-README.TXT and also copied to C:\Users\Public\bgqhm_NOTE.txt—both include a hard-coded e-mail address (bgqhm@onionmail[.]org) and a Tor link for chat.

  • Broader Impact:

  • Early reports emanated from South-East Asian manufacturing and publishing houses, which suggests that initial spam waves were geo-targeted via indigenous-language themed lures.

  • The use of Discord CDN for payload staging mirrors 2023-2024 “loudswitching” tactics—a departure from previous reliance on Tor or bulletproof hosters—complicating traffic-deny-listing for infosec teams.

  • Because it pre-dates the latest Microsoft crypto-currencies ransomware bounty program, researchers are actively soliciting samples for reverse-engineering; thus the threat landscape may remain fluid over the next 3–6 months.

Stay vigilant, enforce layered defenses, and maintain offline, verified backups. Doing so is still your best assurance against .bgqhm or any subsequent ransomware wave.