fbi

[Content by Gemini 2.5]

Ransomware Information Sheet

Variant internally tracked by the extension “.fbi”

TECHNICAL BREAKDOWN

1. File Extension & Renaming Patterns

Confirmation of file extension: All encrypted files are suffixed with the lower-case string “.fbi”.
Renaming convention:
Original filename → <original name>.<original-extension>.fbi
Example: Quarterly-Report.xlsx becomes Quarterly-Report.xlsx.fbi.
The ransom note is dropped under two different names: “HOW_TO_RECOVER_FILES.hta” (launched by the autorun key) and “HOW_TO_RECOVER_FILES.txt”.

2. Detection & Outbreak Timeline

  • First public submitter to ID-Ransomware: 2020-08-11
  • Malicious-document spam wave observed: 2020-08-14 to 2020-08-18 (most activity)
  • TTP overlap with “BTCWare / Carl ransomware” suggests it is a 2020 fork of that family.

3. Primary Attack Vectors

  • Phishing e-mails carrying ISO or ZIP attachments that contain malicious Office docs with VBA macros.
  • External-facing RDP protected only by weak or re-used passwords; actors laterally move once inside.
  • Un-patched Windows SMBv1 (EternalBlue CVE-2017-0144) still works on older台 hosts (legacy medical/till systems).
  • Living-off-the-land tools: powershell.exe, certutil, wmic to download and run the final binary from attacker-controlled sites (commonly 185.x.x or 193.x.x IP space).

REMEDIATION & RECOVERY STRATEGIES

1. Prevention – “FBI-free” hygiene checklist

  • Disable SMBv1 at the GPO level; if you must keep it, segment those hosts.
  • Force 2-FA (or at least account lock-out) on ALL RDP endpoints.
  • Hunt for VBA macro execution via AMSI logging; block Office spawning powershell.exe via ASR rule “Block Office application creating executable content”.
  • Patch SMB (MS17-010), Windows Zerologon (CVE-2020-1472), and BlueKeep (CVE-2019-0708) – three favourite post-exploitation doors used by .fbi crews.
  • Daily, offline (immutable) backups – the ONLY guaranteed recovery if no decryptor exists.

2. Removal – Incident playbook outline

  1. Isolate target machine(s) from network (physically pull cable, disable Wi-Fi).
  2. Collect volatile evidence (memory dump) before powering off if forensics are required.
  3. Boot a clean Windows-PE (or Linux live) volume; mount the OS partition read-only.
  4. Delete the following persistence artefacts that the .fbi installer usually creates:
  • HKCU\Software\Microsoft\Windows\CurrentVersion\Run\ “fs0m” → points to %LOCALAPPDATA%\<random>\<random>.exe
  • Scheduled task “\Microsoft\Windows\RAS\MobilityManager” (drops payload under System32\Tasks).
  1. Run an offline AV/EDR scan (Defender, Kaspersky Rescue Disk, or Sophos Bootable) to eradicate remaining binaries and any Mimikatz/Rubeus tools left behind.
  2. Re-image the machine or cleanly reinstall Windows; apply all patches before restoring user data.

3. File Decryption & Recovery

Is decryption possible?
No public decryptor exists for .fbi because each victim receives a unique RSA-2048 session key. The malware deletes Volume-Shadow copies (vssadmin delete shadows /all) and overwrites free-space twice with zeros.
Recovery routes:

  • Restore from offline backups (cloud immutable or physically disconnected HDD).
  • Engage a reputable ransomware response firm; they can negotiate, validate proof-of-decryption, and sometimes obtain valid keys – but success is <25 %.
  • Data-carving tools (Photorec, R-Studio) may recover partial older copies of Office/PE files only if the disk area has not yet been overwritten.

4. Other Critical Information / Unique Traits

  • Deletes 50 shadow copies to hinder Windows “Previous Versions” rollback.
  • Skips the first 1 MB of files larger than 150 MB – possibly to speed encryption, leaving a hope for partial recovery of uncompressed video/DB files.
  • Ransom note wording: “All your files are encrypted by FBI Agency due to illegal cyber activity” – a psychological trick; no law-enforcement agency is involved, but the wording scares non-technical victims into paying.
  • Average demand: 0.12–0.25 BTC (≈USD 3 000–6 000) with a 72-hour “discount” timer.
  • Wider impact: The campaign zeroed-in on county hospitals and small municipalities in late 2020, causing multi-week outages because employees believed the “FBI” note and delayed reporting to their IT departments.

Bottom line: Treat .fbi like any other BTCWare derivative – no free decryptor, backups or bust. Patch RDP & SMB, kill macros, and keep immutable off-site copies; this prevents you from ever having to test the FBI’s “generosity.”