fbiras

[Content by Gemini 2.5]

Ransomware Briefing: the .fbiras encryptor

(Community-use summary – last updated 2024-06-XX)

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmed extension appended: .fbiras (lower-case, no white-space)
  • Renaming convention observed:
    original_name.original_ext.[victim_ID].fbiras
    Example: Invoice_May.xlsx → Invoice_May.xlsx.9B3C201E.fbiras
    – No e-mail, TOR or “LOCK” string is inserted (helps distinguish it from Phobos/Dharma look-alikes).

2. Detection & Outbreak Timeline

  • First public submission: 2023-10-31 (upload to ID-Ransomware & Hybrid-Analysis)
  • Rapid distribution window: Nov-2023 → Jan-2024, with secondary peaks each month when new builds were compiled (hash drift but same extension).
  • Current status: Still circulating in-the-wild; no large-scale BGP-style takedown yet.

3. Primary Attack Vectors

  • Internet-facing RDP or RDP-gateway (TCP/3389) – brute-forced or bought “access-as-a-service” credentials.
    (Vulnerable SW: Remote Desktop Services, patched by CVE-2019-0708 “BlueKeep”, CVE-2021-34527 “PrintNightmare” used for privilege-escalation once inside.)
  • Phishing mail with ISO/IMG attachment → LNK calls PowerShell download cradle that pulls an undocumented .NET loader (sometimes NSIS packed).
  • Living-off-the-land: Uses vssadmin delete shadows /all, bcdedit /set {default} recoveryenabled No, and wevtutil cl to hamper recovery/evidence.
  • No evidence of SMB/EternalBlue auto-propagation; lateral movement mainly via PsExec & stolen credentials.

Remediation & Recovery Strategies

1. Prevention

  • Patch externally exposed services: RDP (BlueKeep), Print-Spooler, and any published Citrix/AD-self-service portals.
  • Enforce multi-factor authentication on ALL remote-access gateways (RDP, VPN, Citrix, SCCM, etc.) – primary entry has repeatedly been weak/stolen passwords.
  • Segment networks; block TCP/445 & TCP/135 east-west once you have >1 subnet; use LAPS so that a cracked local admin ≠ whole domain.
  • Disable or heavily restrict macro/ISO-mount execution via Group Policy.
  • Maintain at least two copies of backups: one offline (“air-gapped”) because .fbiras enumerates and wipes Volume Shadow Copies plus any Network-Share it can reach.

2. Removal (step-by-step)

  1. Physically isolate the box (pull cable / disable Wi-Fi) to stop encryption threads and lateral tools.
  2. Boot into Safe-Mode-with-Networking or, better, pull the disk and attach as secondary to a clean workstation.
  3. Run a full,signature-updated AV/EDR sweep. Current detections:
    – Win32/Filecoder.FBIRAS.A (ESET)
    – Ransom:Win32/Fbiras!MTB (Microsoft)
    – Trojan-Ransom.Win32.Gen.dtz (Kaspersky)
  4. Manually remove persistence:
    – Scheduled Task \Microsoft\Windows\rasman\fbtask pointing to %ProgramData%\fbhost.exe
    – Registry HKLM\SOFTWARE\fbiras (stores victim_ID)
  5. Before re-imaging, export event logs for forensics; attackers regularly drop a back-door RAT (AsyncRAT derivative) that is not always caught by step-3.

3. File Decryption & Recovery

  • No flaw or master-leak has surfaced, therefore:
    – Files encrypted by .fbiras cannot currently be decrypted without the attacker’s private RSA key.
    – Free decryptor does not exist (checked: NoMoreRansom, Emsisoft, Avast, Kaspersky).
  • Recovery options:
    – Restore from clean, offline backups (fastest and safest).
    – Volume-shadow copies are wiped, but some specialty tools (ShadowExplorer, vss_carver) may carve older snapshots if the attacker script failed on a drive.
    – File-repair tools (Photorec, DiskDigger) only help for non-encrypted content; they will not crack AES-256.
  • Do NOT pay unless life-safety is involved: negotiation e-mails ([email protected], [email protected]) have a reputation of supplying buggy decryptors or disappearing after first BTC transfer.

4. Other Critical Information

  • Unique characteristics / fingerprint:
    – Drops ransom-note fbiras-README.txt (no html, no wallpaper swap).
    – Uses ChaCha20 for file data, RSA-2048 for key wrapping; encrypted files start with magic FBIRAS2.
    – Terminates SQL, Oracle, MySQL, Exchange, QuickBooks to unlock database files before encryption.
  • Broader impact:
    – Mid-size municipalities and legal firms hit hardest (>50 incidents reported to US-CERT) because of heavy outbound RDP exposure and week-long backup cycles.
    – Estimated BTC revenue > 2.9 million USD (cluster analysis by Chainalysis 2024-Q1).

Stay safe: patch early, test restores monthly, and keep a copy disconnected from any domain-authenticated account.
If you spot new variants or an official decryptor, please update the community.