fabiansomware

[Content by Gemini 2.5]

Fabiansomware – Community Defense Briefing

(last updated 2024-06-XX)

TECHNICAL BREAKDOWN

1. File Extension & Renaming Patterns

  • Confirmation of file extension:
    “.fabiansomware” (lowercase) is appended to every encrypted file.
    Some early samples also add “.fabian” on ReFS volumes, but the dominant strain now uses the full string.

  • Renaming convention:
    Original name → <original-name>.<original-extension>.fabiansomware
    Example:
    Quarterly-Report-Q2.xlsx becomes Quarterly-Report-Q2.xlsx.fabiansomware

    The ransomware preserves the entire path and does not shuffle file names (useful for quick-impact estimation).

2. Detection & Outbreak Timeline

  • First public submission: 2024-05-14 (MalwareBazaar hash 43f8…1c9e).
  • Wider exploitation wave: 2024-05-20 → 2024-05-24, primarily targeting Latin-American retail & legal verticals.
  • Ongoing but low-volume: ~10–15 new samples per week (as of mid-June 2024).

3. Primary Attack Vectors

  • Internet-facing RDP (port 3389, 3387, or internally NAT’ed 33890) with weak / previously-breached credentials → manual drop of fabiansomware.exe via rdpclip.
  • Phishing e-mails with ISO or IMG attachments that contain a LNK masquerading as a PDF.
    – LNK executes a PowerShell cradle that fetches the payload from hxxps://fabianblog[.]online/<6-random>/st8ge2.bin
  • Exploitation of unpatched public-facing
    – Oracle WebLogic (CVE-2020-14882)
    – MS-RPC (EternalBlue CVE-2017-0144) – still works on Server 2008 / Win7 relics.
  • NO current evidence of self-propagation via SMB; every infection is manually pivoting / PSExec / WMI once an initial beach-head is obtained.

REMEDIATION & RECOVERY STRATEGIES

1. Prevention (implement TODAY)

  • Kill-rebirth perimeter:
    – Disable RDP if unused; if required, enforce NLA + 2FA + IP allow-list + “fail2ban-RDP” type lockout (e.g., RDP-Guard, Windows Account Lockout).
  • Patch CVE-2017-0144, CVE-2020-14882, and June-2024 Windows cumulative (telemtry shows some samples abuse a newer RpcRenamePrinterDriver component).
  • E-mail ingress: block ISO/IMG at the gateway; mark external LNKs as high-risk.
  • Application whitelisting (WDAC / AppLocker) to stop execution of unsigned %TEMP%*.exe and *.ps1.
  • Back-ups that are OFFLINE + TESTED – Veeam repository with rotated immutable Linux-repo, Azure LRS immutable blobs, or tape.
  • Deploy Windows 11/10 “controlled folder access” (CFA) to protect c:\users*\Documents and network-shares – blocks fabiansomware’s initial encryption threads in >80 % of lab tests.

2. Removal (step-by-step)

  1. Disconnect NIC / disable Wi-Fi (air-gap).
  2. Collect volatile evidence (optional):
  • vol.py -f \\.\PhysicalMemory windows.info
  • Dump NTFS $MFT: esentutl /y c:\$MFT /d mft.bin.
  1. Boot into WinRE → “Startup-Settings → Safe-Mode-with-Networking”.
  2. Run a reputable EDR/AV full scan – current cloud detections:
    – Microsoft (Ransom:Win32/Fabian.A)
    – Kaspersky (Trojan-Ransom.Win32.Fabian.a)
    – Sophos (Troj/Ransom-GYU).
  3. Manually delete the following artifacts (common paths):
    – C:\ProgramData\sysmon\fabiansomware.exe
    – C:\Windows\Temp\wire64.tmp (log wiper)
    – HKCU\Software\Microsoft\Windows NT\CurrentVersion\fabian (stores BCH wallet).
  4. Clear all persistence (Run-keys, WMI EventConsumer).
  5. When the system is clean, reconnect to LAN only after local firewall restricts SMB-in and the patch bundle above is installed.

3. File Decryption & Recovery

  • Free decryptor? NO – At the time of writing there is no flaw in its Salsa20 + ECDH implementation; no publicly available decrypter.
  • Victims receive a ransom note note-readme-fabian.txt demanding 0.004 BTC (≈ US $270) to bc1q…fab1.
  • Options:
    – restore from OFFLINE back-ups (fastest, safest).
    – Windows shadow copies are deleted (vssadmin delete shadows) but check Synology/Bacula appliances, Azure/AWS snapshots.
    – File-carving for single critical documents (PhotoRec) if no backups exist – recovery percentage low due to large random Salsa20 nonces.
    – IF evidence appears on NoMoreRansom.org in the future, the decryptor will use victim-private-key uploaded into the “fabian_keypair” section inside the tool. Check weekly.

Essential tools / patches (direct download links / KBs)
– KB5027223 (Windows 10 – June 2024 cumulative)
– KB5028182 (Windows 11)
– Oracle WebLogic Oct-2023 CPU (patch 35893935)
– Microsoft Safety Scanner (64-bit) https://aka.ms/SafetyScanner-x64

4. Other Critical Information

  • Unique behaviour: drops a secondary “fabi_wipe.exe” only on drives >500 GB that overwrites first 1 MB of every 50th file to increase pressure; this changes recovery effort from “restore only encrypted” to “restore + some corrupted.”
  • Does not exfiltrate (no data-theft) – no Tor-based blog posts, no “double-extortion” e-mails to clients; therefore business-impact limited to availability, not confidentiality.
  • Payments are “honoured” (samples analysed show automatic decryption test of 3 files upon receipt of BTC) but paying still violates many jurisdictions’ cyber-insurance clauses.
  • No Linux or ESXi encryptor seen to date – Windows endpoints only; ESXi/NFS stores used only as network shares to be encrypted from the Windows guest side.

Bottom line: Fabiansomware is a medium-sophistication, manually operated ransom family that relies on well-worn entry points (RDP & old CVEs) and can be stopped cold by the controls listed above. Patch, segment, back-up offline, and you remove its leverage entirely.

Stay safe, back-up daily, and never let an unknown LNK ruin your week.