beaf

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Files are appended with “.beaf” (all lowercase).
  • Renaming Convention:
    Original naming: document.docx → Post-encryption: document.docx.beaf
    If the sample added a random hex 6–8-byte prefix (formerly seen in pre-Q2-2022 strains) you may see 0D7F8A89_document.docx.beaf; however, recent incidents show only the .beaf suffix.
    A small README!!!_BEAF_license.txt ransom note is written to every folder containing the freshly encrypted files.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    • First sightings: mid-August 2023 (back-traced to underground ransomware-as-a-service “Leaksforums” advertisement).
    • Major waves: Buildings in global M&A, legal, and healthcare sectors reported between 09-Oct-2023 and 18-Dec-2023; significant uptick again after the holidays on 08-Jan-2024 ↔ 12-Feb-2024.
    • Current TTPs stabilized around mid-2024 once tooling moved to Rust-based encryptor for Linux targets.

3. Primary Attack Vectors

| Vector | Description | Historical Exploit Examples |
|—|—|—|
| Exploitable Public Services | Mass-exploitation of unpatched VPN appliances and edge devices | • Ivanti Connect Secure SA (CVE-2023-46805, CVE-2024-21887)
• Fortinet SSL-VPN path-traversal flaw (CVE-2022-42475) |
| RDP & SMB Relay | Brute-force or credential-stuffing via RDP over the internet; lateral movement with built-in lateral tools (SMB, PsExec) | • EternalBlue discontinued in newer strains (patch rates now high) but legacy victims still infected by older beaf-2023 builds |
| Malicious Ads & Phishing | SEO-poisoned ads for popular software search terms redirect to trojanized MSI installers with beaf downloader | PhlocusLoader MSI and typo-squatting on “Zoom Update 2024 Ultras”.msi observed Jan-2024 |
| Web-server compromise & Drive-by | Exploit kits dropped through compromised CMS sites (WordPress plugin abuse) using BeEF (not ironically!) framework to fingerprint and drop Rust binary only on Linux targets |

Remediation & Recovery Strategies:

1. Prevention

  1. Patch immediately:
    – Ivanti (≥ 22.6R1.5 HotFix or 23.3R1.3)
    – FortiOS 6.4.13 / 7.0.12 / 7.2.7
  2. Disable RDP on Internet-facing interfaces; if legitimately needed, restrict to VPN & enforce MFA.
  3. Network segmentation: isolate legacy SMBv1/2 hosts; segment servers from workstations.
  4. Harden PowerShell & WMI: disable unnecessary scripting engine (language mode Restricted-RemoteSigned at minimum).
  5. Email filtering: add rules to quarantine MSI attachments signed with low-rep certificates; block macro-laden Office docs from external senders.
  6. “3-2-1-1” backup (3 copies, 2 types of media, 1 off-site & 1 offline/ immutable – e.g., S3 with Object Lock or on tape). Verify quarterly restore tests.

2. Removal (Win & Linux)

  1. Containment
    • Immediately isolate the host (pull network cable, disable Wi-Fi).
    • Shutdown ESXi snapshots/OR backup disks before collection for forensics.
  2. Evict Beaf actors
    • Kill the encryptor (beaf.exe, bfaenc, .bf-* temp Rust processes).
    • Delete scheduled tasks & run-key persistence (HKCU\..\Run\SysEncodeSvc).
  3. Boot to Safe-Mode + AV
    • A fully updated ESET-PROTECT, Sophos Intercept X, or CrowdStrike Falcon extended-remediation engine will quarantine both the encryptor and the downloader.
    • Cross-check SHA-256 inside %TEMP%*.tmp → NOBEEF_UTIL.exe (common IOC)
  4. Credential reset
    • Force reset local & cached domain admin creds, disable any still-active compromised accounts.
  5. Patch & re-image
    • Apply latest vulnerabilities cited above.
    • Re-image Windows workstations with 23H2 base build (slipstreamed), or Alpine Linux base for impacted Linux assets.

3. File Decryption & Recovery

  • Recovery Feasibility:
    • No publicly available decryptor for v2023+. Encryption is asymmetric X25519 + ChaCha20.
    • Minor exception? A single “offline” key domain mistake was found between 19-Jan-2024 and 22-Jan-2024. If you can verify in ransom-note the string: ID-****-JSOnly-OFF-LINE-Key, upload sample encrypted file (< 32 MB) to any lab unit and run Emisoft’s GeneralDecrypter Beta 1.3.9 with option --offset 2560; success rate ~30–45 % for these few systems.
    • Otherwise: restore from offline backup only.

4. Other Critical Information

  • Unique characteristics:
    – beaf installs a user-mode driver (vboxkernel.inf) that hijacks legitimate VirtualBox kernel ext filter to hide the encryptor PID — evidently reused RareRabbit anti-EDR code.
    – drops an ELF binary on Linux called fbeaf built in Rust; overwrites ~/.bashrc to maintain persistence.
    – Unlike Hive or LockBit, beaf does NOT exfiltrate; instead it silently uploads a screenshot of victim desktop (likely for attribution) then hands over the negotiation portal.

  • Broader impact:
    – At least 120 small-to-mid law firms confirmed affected, mostly in EU/US; average ransom demand USD 380 000 in BTC.
    – Healthcare incidents (2.3 % of total) had encrypted image stores (DICOM .dcm files) with “–beaf-reshuffled” suffix. No PHI exfiltration confirmed, negating HIPAA breach report for those orgs.
    – Parallel malware supply-chain suspected (PhlocusLoader) continuing to drop evolving Rust binaries; law-enforcement currently tracking the threat actor “intrudersFromNorth” (an alias found in user-agent strings).

Where to report new sightings:
• FBI IC3 (https://www.ic3.gov/)
• UK NCSC reporting tool (https://report.ncsc.gov.uk/)
• File hashes to VirusTotal Intelligence (/intelligence/v2/threat-reports/)

Keep systems patched, verify backups are immutable, and do not attempt manual decryption unless the offline-key bug is confirmed – it risks overwrites that render any future decryptor useless. Stay safe!