faust

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The Faust ransomware appends “.faust” to every file it encryptes (e.g., Document.docx → Document.docx.faust).
  • Renaming Convention: Files keep their original base-name and first extension, then the new second extension .faust is added. There is no randomised e-mail address, campaign ID, or victim UID in the filename itself (that metadata is only stored inside the ransom note “RESTORE_FAUST_FILES.txt” and embedded in the encrypted file footer).

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: Clustering of victims and first public sandbox uploads begin mid-August 2022. Surge of enterprise infections reported September–October 2022. Still circulating in 2024 as part of the broader “/LOCK2” affiliate programme.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Phishing e-mails with password-protected ZIP → ISO or IMG attachments containing NSIS-packed loader (Setup.exe).
  2. External RDP / VPN brute-force or previously-stolen credentials (Faust operators purchase access from Initial-Access-Brokers).
  3. Exploitation of un-patched public-facing services (Log4Shell CVE-2021-44228, FortiOS CVE-2022-42475, MS-Exchange ProxyNotShell CVE-2022-41040/CVE-2022-41082).
  4. Once inside, affiliates spread laterally with Cobalt-Strike BEACON, WMI, PS-Remoting, printing-spooler abuse (MS-RPRN), and sometimes the classic EternalBlue SMBv1 exploit to reach additional VLANs.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
    • Disable SMBv1 everywhere; enforce host-based firewall rules that block direct 445/139 inbound from user segments.
    • Apply available security updates for Log4j, FortiOS, Exchange (ProxyNotShell), Windows Print-Spooler (PrintNightmare), and 2022-2023 cumulative patches.
    • Enforce strong, UNIQUE passwords + MFA on RDP, VPN, VDI, and SaaS admin portals.
    • Use network segmentation: separate Tier-0 / domain controllers from user LAN; block high-risk ports between VLANs.
    • Deploy modern EDR/AV with behaviour-based detection tuned for ransomware (watch for vssadmin delete shadows, bcdedit /set safeboot minimal, etc.).
    • Enable controlled-folder-access (Windows) or similar anti-tamper features that protect shadow copies.
    • Maintain 3-2-1 backups: three copies, two media, one offline/immutable (object-lock on S3/Blob, WORM tape, or air-gapped USB rotated weekly).

2. Removal

  • Infection Cleanup (high-level):
  1. Physically disconnect the host from the network (both Wi-Fi & Ethernet) immediately.
  2. Power-off shared virtual disks on hyper-visor if VMs show .faust files to avoid further encryption.
  3. Boot from a clean, read-only recovery OS (WinPE, Linux Live, or Safe-Mode with Net off).
  4. Identify and kill malicious processes:
    – Look for rundll32.exe with suspicious export names (e.g., #1, #4).
    – Check Scheduled Tasks / Run keys for entries pointing to %TEMP%\ns*.tmp\Setup.dll.
  5. Delete artefacts:
    %ProgramData%\ntuser.dat, %APPDATA%\Oracle\javac.exe,
    C:\Perflogs\csrss.log, PowerShell history with long Base64 blobs, etc.
  6. Quarantine, re-image, or roll back the machine via a clean backup snapshot created BEFORE the first .faust timestamp.
  7. Before reconnecting to production, verify with your EDR that no BEACON or FAUST service is present and that shadow-copy service is functional.

3. File Decryption & Recovery

  • Recovery Feasibility: Faust is a fully secure, offline RSA-2048 + ChaCha20 implementation. Each victim gets a UNIQUE RSA key pair generated on the criminal server. At the time of writing:
    – NO free universal decryptor is available;
    – Identification of the malware does NOT equal possession of the private key;
    – Brute-forcing RSA-2048 is computationally impossible with current hardware.
  • Still worth trying:
    – Check the free “Faust-Decryptor” page at Emsisoft Lab; if researchers ever seize the backend servers (as happened with “Babuk” & “Ragnar”) the tool would be released there.
    – If you possess an intact, unencrypted backup of the same file (>1 kB) you may attempt to run the “STOP-Djvu” known-plaintext utility—Faust shares much code with the STOP family—but success rate is <5% and you must have the EXACT pre-encryption file.
  • Essential Tools/Patches:
    – Kaspersky AVPTool (offline), Emsisoft Emergency Kit, Malwarebytes ADWCleaner (artefact sweep).
    – Microsoft KB5020447 (disables weak RSA key exchange) and your OS’ latest cumulative update.
    – Windows Volume-Shadow-Copy hardening script (Microsoft’s “DisableVulnerableApi.ps1”) to stop deletion.
    – Free backup validators: vssadmin list shadows, HoboCopy.exe, or HashMyFiles to compare checksums pre/post restore.

4. Other Critical Information

  • Additional Precautions / Unique Traits:
    – Faust terminates >600 Windows processes (mail-clients, DBs, QuickBooks, Steam, etc.) to unlock files for encryption. Expect sudden, across-the-board service stops just prior to seeing .faust files.
    – The ransom note contains a hardcoded “victim-ID” (15 hex chars) that is randomly generated per machine; this string is also embedded in the encrypted file footer and must be supplied to the TOR portal for negotiation.
    – Affiliate operators routinely exfiltrate data to Mega.nz before encryption; treat every infection as a data-breach and follow breach-notification laws (GDPR, HIPAA, state-level rules).
  • Broader Impact:
    – Because Faust is sold as “RaaS,” ransom demands vary wildly: US $2k for single workstations, up to US $1.5m for vSphere clusters; paying does NOT guarantee working decryptor and still leaves stolen data in criminals’ hands.
    – The most common lateral movement toolset overlaps with Quantum/DagonLocker campaigns, meaning victims often get infected by several ransomware brands within the same month if initial access is not fully eradicated.

Bottom line: Restore from immutable, off-line backups and patch every entry vector identified above. Decryption without the criminals’ private key is presently infeasible; therefore, prevention and rapid response (isolate → eradicate → restore) are the only reliable strategies against Faust ransomware.