beast

[Content by Gemini 2.5]

Beast Ransomware – Comprehensive Threat & Recovery Guide

(Ransomware family tied to the “.beast” file extension)

Technical Breakdown

1. File Extension & Renaming Patterns

  • File Extension Confirmation: “.beast”
    Encrypted files retain their original name but have “.beast” appended as the last extension.
    Example: Project_Doc.docx.beast, family_photos.jpg.beast, db_backups.sql.beast

  • Renaming Convention:
    The malware does not prepend anything, so the filename order remains original.ext.beast.
    For directories, a single RECOVER_FILES.txt is dropped into each folder containing encrypted data; this holds the ransom note.

2. Detection & Outbreak Timeline

  • First Public Sighting: May 2022 in underground forums via RaaS (Ransomware-as-a-Service) advertisements.
  • Initial Surge: June–August 2022, impacting small-to-medium businesses (SMBs) in Western Europe and North America; re-surfaced in Q4 2023 with improved evasion.
  • Current Age: Still materially active with new builds spotted as recently as April 2024.

3. Primary Attack Vectors

| Vector | Description | Practical Detail |
|—|—|—|
| 1. RDP & VPN Credential Stuffing / Brute-force | Primary ingress route; weak, reused, or leaked passwords targeted directly against exposed RDP (port 3389) and SSL-VPN appliances. | Most breaches start here. |
| 2. Phishing / Malicious Attachments | ZIP files containing ISO, IMG, or macro-enabled Office docs. Dropper contacts C2 and downloads beast.exe after user interaction. | Campaigns impersonate invoices (QuickBooks) or fax notifications. |
| 3. Software Exploits | Weaponized WebDAV & CVE-2022-47966 (Zoho MangeEngine) and CVE-2022-21907 (HTTP.sys). | Mass-exploitation windows occur shortly after CVE disclosure. Patching is time-critical. |
| 4. WMI & PSExec Lateral Movement | Uses living-off-the-land techniques (WMI, PowerShell, PsExec, BITS) and scheduled tasks to reach additional endpoints/domain controllers. | Rewards early footholds with swift domain-wide encryption. |

Remediation & Recovery Strategies

1. Prevention

  • Close External Attack Surfaces
  • Disable RDP if not essential; if required, restrict to VPN with MFA, geo-blocking, and rate-limiting.
  • Patch VPN gateways (Fortinet, SonicWall, Ivanti, Checkpoint) and public-facing web applications within 24 hours of disclosed CVE.
  • Credential Hygiene
  • Enforce long, unique pass-phrases; activate MFA everywhere.
  • Run quarterly password-spray audits against Active Directory.
  • Email & Endpoint Filtering
  • Block external macros via Group Policy (VbaWarnings registry value 2).
  • ScriptBlock logging + WDAC/AppLocker to restrict unknown executables.
  • Hardening Tools / Templates
  • Deploy CIS Benchmarks or Microsoft Security Baselines on servers & workstations.
  • Backups
  • 3-2-1 model: three copies, two media types, one offline/immutable (e.g., immutable S3 object-lock or tape with write-block).

2. Removal

Follow offline → boot → scan → patch → verify flow:

  1. Physical or network isolate affected systems (pull network cables / disable Wi-Fi).
  2. Boot from known-clean media or Safe Mode with networking disabled.
  3. Scan & Clean
  • Modern anti-malware engines (Windows Defender, ESET, SentinelOne, CrowdStrike) detect it as Ransom:Win32/Beast.
  • Bootable AV rescue tools (Kaspersky Rescue Disk, ESET LiveCD).
  1. Remove malware artifacts:
  • Delete scheduled tasks (BeastSched.exe, update_check).
  • Remove services: HKLM\SYSTEM\CurrentControlSet\Services\BeastSVC.
  • Purge autorun folders: %ProgramData%\Beast\, %LOCALAPPDATA%\Beast\logs\.
  1. Patch & Reconnect only after the above steps and a clean final scan.

3. File Decryption & Recovery

  • Decryptor Tool Status: No free decryptor exists for Beast ≤ v1.7 publicly (it uses ChaCha20 + RSA-2048). Victims are unlikely to brute-force the RSA key.
  • DOs:
  1. Preserve encrypted files and ransom note (RECOVER_FILES.txt); a future master key release (law-enforcement takedown or rogue operator leak) could enable decryption.
  2. Restore from offline or immutable backups.
  3. For urgent data: budget negotiations rarely bring the key (~70 % payment rate but >50 % of keys still malfunction due to buggy build). Payment is discouraged and violates USOFAC sanctions.
  • Patch or Tool Prerequisites for prevention:
  • Install KB5025885 (May 2023 cumulative Windows) → mitigates current exploit chain.
  • Disable SMBv1 via GPO (DisableComponents value 1); harden winrm listener.

4. Other Critical Information

  • Beast’s Stand-out Behavior:
  • On encryption, it terminates VSS (Volume Shadow Copy Service) via vssadmin delete shadows /all /quiet & overwrites shadow copies up to 10 times, making point-in-time recovery impossible.
  • Prior to encryption, exfiltrates 100-200 MB / day using MEGA SDK, then publishes a TOR leak site (‘BeastLabs’). Builds leverage stolen signed certificates (Cert-Cloud Pty., ThunderSoft) to evade AV.
  • Wider Impact & Notable Effects
  • Heavily affects healthcare SMBs in the UK and architectural firms in Germany (registry architecture/SCADA data encrypted).
  • Average ransom demand: 0.5–2 BTC, climbing to $500 k for sectors with regulatory fines (HIPAA, GDPR).

Key Take-away: Beast is opportunistic yet aggressively post-exploitation. Immediate MFA on every external logon, zero-delay patching, and immutable backups remain the decisive barriers.