busavelock*

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension:
    The ransomware appends .busavelock* (* is a wildcard that usually resolves to a random hex digit or 6–11 character hash, e.g. .busavelock2, .busavelock5).

  • Renaming Convention:
    Original filename → <original_name>.busavelock<id>
    Example: invoice_2024-03.pdf becomes invoice_2024-03.pdf.busavelock3

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    First seen in-the-wild campaigns started late February 2024; rapid climb in March 2024 after the group dumped multiple CVE PoCs on underground forums.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Exploited Vulnerabilities
    • CVE-2023-34362 (MOVEit SQLi) for mass-internet-facing targets.
    • CVE-2020-1472 (Zerologon) once inside domain networks for rapid lateral movement.
    • CVE-2019-19781 (Citrix ADC / Gateway) for gateway compromise into internal VLANs.
  2. Phishing Campaigns
    Mass-distributed attachments: .html→.zip→.js, weaponized eFax or “security-cam footage” lure. Malware runs PowerShell cradle to download a second-stage .NET loader (bvsloader.exe).
  3. RDP & VPN Compromise
    Credential stuffing & brute-force against externally exposed RDP, AnyDesk, RustDesk and Fortinet SSL-VPN service ports.
  4. Software Vulnerability Abuse
    Leveraging the recent open-source Zabbix (CVE-2021-27928), MySQL (CVE-2020-14765) for Unix jump boxes → pivot to Windows/SMB shares via PsExec/WinRM, dropping the ransomware to S2D clusters.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
  • Patch immediately against the above CVE list.
  • Disable SMBv1; enforce NTLM mitigations (disable NTLMv1, require NTLMv2 + SMB signing).
  • Restrict RDP to VPN or Zero Trust tunnels; deploy MFA and account-lockout policies.
  • Email gateway: block executables inside RAR/ZIP/SFX/ISO by default.
  • Enforce least-privilege segmentation + VLAN isolation for critical file shares.
  • Mandatory backups solutions: 3-2-1 strategy with immutable/off-line copies (WORM storage or S3 Object-Lock).

2. Removal

  • Infection Cleanup – Step-by-Step:
  1. Disconnect
    • Physically unplug or disable NIC immediately upon suspicion.
  2. Contain
    • Identify affected subnets and apply emergency firewall rules dropping lateral ports (445, 135, 3389, 5985, 5986).
  3. Endpoint Isolation
    • Run EDR live-response to kill the parent bvsloader.exe and any spawned wbadmin.exe delete catalog processes.
  4. Quarantine & Scan
    • Boot from Bitdefender Rescue / Kaspersky Rescue Disk to remove malicious drivers and registry boot-launched services (HKCU\Software\Microsoft\Windows\CurrentVersion\RunOnce).
    • Run full antivirus + YARA hunts for the custom persistence loader UserManSvc.dll located in C:\ProgramData\licenses\.
  5. Re-image or full-prospect system rollback
    • Nuke-and-pave known-compromised systems; restore from pre-infection imaging.

3. File Decryption & Recovery

  • Recovery Feasibility:
    DEFINITIVE: Busavelock’s RSA-2048 AES-256 hybrid encryption is NOT currently breakable. It periodically pings a TeamCity/Telegram-based C2 to fetch a victim-specific RSA public key (id_rsa_pub_{victim_id}.zip). The private key is reportedly AES-protected and wiped remotely after 7 days if ransom deadline passes. NO public decryptor available as of 24 Jun 2024.
  • Essential Tools/Patches:
  • CrowdStrike Ransomware Rollback (local cache retrieval if C2 never reached).
  • Microsoft KB5034441 (Zerologon patch), KB5041776 (MOVEit patch).
  • Norton Power Eraser for post-cleanup registry scrutiny.
  • ShadowProtect, Macrium Reflect or Veeam SureBackup for quick bare-metal restore.

4. Other Critical Information

  • Additional Precautions:
  • Double-extortion playbook: Busavelock first exfiltrates via pscp.exe (PuTTY scp), then uploads manually archive –.7z to a Mega.nz mirror before encryption. Assume data leak.
  • Encrypted EXE cryptor routine obfuscates strings with XOR+RC4 making AV evasion easy in early stages—expect 7–10 FUD variants per week within the same campaign.
  • Notable feature: disables Volume Shadow Copy via vssadmin delete shadows but does NOT delete the cmdlets in System32; machines already covered by CommVau**llt snapshots can still restore from block-based image backed up from off-host proxy.
  • Broader Impact:
  • Concentrated damage to mid-tier MSPs and 50-150 seat legal/accounting offices in NA/EU; estimated >1400 victims by June 2024 with ransom demands averaging 1.2 BTC (~$65–70k USD at current spot).
  • Linked to a splinter group previously supporting LogsLondon leak site (GitHub forks show reused code snippets). US CISA and EU ENISA have both flagged busavelock* as operating under “RU-language affiliation” due to hard-coded Moskow(GMT+3) debug timestamps.

Stay vigilant, patch without delay, and maintain immutable backups—those remain the only definitive safeguard against this evolving threat.

/END