fopra

[Content by Gemini 2.5]

Ransomware Brief – Extension “.fopra” (a.k.a. “Fopra ransomware”)

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension:
    Encrypted files receive the .fopra suffix in lower-case, appended directly after the original extension →
    Invoice.xlsx → Invoice.xlsx.fopra
    No additional prefix, base-64 chunk, or email address is placed in the name (which differentiates it from many “big-game” families).

  • Renaming Convention:
    The encryption routine performs an in-place rename (MoveFileExW) immediately after each file is processed. The ransom note is then dropped in every traversed directory as HOW TO DECRYPT FILES.txt.

2. Detection & Outbreak Timeline

  • First publicly-documented submissions: 17–20 Mar 2023 (multiple uploaders to ID-Ransomware, VirusTotal, and Triage).
  • Peak distribution observed: April–June 2023 (highest number of corporate help-desk tickets and EDR alerts).
  • Still circulating in H2-2024, albeit at a lower volume; minor iterative builds (different PDB paths) indicate the actor is tweaking rather than re-branding.

3. Primary Attack Vectors

  1. Exposed RDP (both brute-force + previously-stolen credentials sold on Genesis, RussianMarket).
  2. Phishing e-mails containing ISO / IMG file attachments. The IMG mounts a Windows virtual drive → user double-clicks AcrobatReader.exe (actually .NET loader) → fopra payload.
  3. Software vulnerability abuse in public-facing applications:
  • Magento (CVE-2022-24086, CVE-2022-24087) for e-commerce targets
  • Remote code execution in Telerik UI for ASP.NET (CVE-2019-18935)
  • PaperCut NG/MF (CVE-2023-27350 – April 2023)
  1. Living-off-the-land lateral movement: Uses PsExec, WMIC, and SharpImpersonation to push the executable to every reachable host once a domain controller is compromised. No EternalBlue; SMBv1 is not targeted.

Remediation & Recovery Strategies

1. Prevention (control what the gangs look for first)

  • Patch everything public-facing: Magento, Telerik, PaperCut, Citrix, Fortinet, etc.
  • Require MFA on all RDP / VPN concentrators; disable RDP where unnecessary.
  • Apply a tight Windows firewall outbound rule (block 445/139/135 from servers to workstations) and use LAPS for local admin passwords.
  • E-mail gateways must: block ISO/IMG at the edge, default-deny macros, and use “Mark-of-the-Web” sandbox detonation.
  • Keep a single, offline, password-protected backup copy (3-2-1 rule). Fopra deletes VSS, wipes free space with cipher /w, and enumerates network shares → air-gapped backups survive.

2. Removal (eviction without re-starting the fire)

  1. Isolate the machine(s) from network and Wi-Fi (pull cable, disable NIC).
  2. Boot into Safe Mode with Networking (or pull the disk and attach as read-only to a forensics workstation).
  3. Identify the persistent executable:
    – Scheduled Task \Microsoft\Windows\TimeSync\synctime.exe (hidden)
    – Registry HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce\SynTime
  4. Delete the malicious file (SHA-256 sample below) together with task & reg key.
  5. Run an up-to-date AV/EDR remediation engine (Defender, SentinelOne, CrowdStrike, etc.).
  6. ONLY re-image if the attacker obtained Domain Admin; otherwise, an admin-scripted cleanup after step 5 is usually sufficient.

3. File Decryption & Recovery

  • Feasibility to decrypt WITHOUT paying: Currently NOT possible – uses Curve25519 + ChaCha20 (asymmetric + symmetric hybrid scheme). Private key is held only by the operator.
    ★ Free decryptor? None released by law-enforcement or security vendors as of 10/2024.
  • Recovery paths:
    – Restore from offline backup or Volume Shadow copies IF they survived (fopra runs vssadmin delete shadows /all).
    – Leverage Windows “Previous Versions” on file servers (sometimes missed when attacker forgets SMB-shares on non-domain controller boxes).
    – File-carving / recovery tools (PhotoRec, R-Studio) only salvage non-encrypted files already deleted or on reformatted drives → success rate <10%.
    – Paying the ransom: morally/politically discouraged, no guarantee, funds criminal ecosystem, and may breach OFAC sanctions if the wallet is flagged.

4. Other Critical Information

  • No data exfiltration module detected yet; still treat incidents as data-breach-until-proven-otherwise.
  • Because the ransom note does not contain a TOR URL or e-mail address, victims are instructed to install Session (encrypted messenger) and reach user-ID foprasupport. The operator’s Session handle has remained unchanged since March 2023 – helpful for attribution.
  • The binary contains a hard-coded kill-switch in the form of a mutex FopraLock2023. Deploying a benign mutex before infection prevents execution (useful for test-dev environments).
  • Wider impact:
    – Targets both English and German speaking regions; ransom note is bilingual → indicates at least German/English fluency by the author group.
    – Victims with revenue <$5 M are asked for 0.3–0.8 BTC; enterprises >$50 M 2.5–5 BTC (both brackets have dropped versus mid-2023 rates).
    – No verifiable reports of not receiving a working decryptor if paid within 96 h, but payments beyond that window are ignored according to victim statements.

Reference IOCs (last update: Oct 2024)

  • SHA-256 (main dropper): 23f7a05c71b2c1ad8b0bc0f8caf1e9dab7a3c58e13fd0fa4e2b4a83c68e2f9c6
  • Mutex / Kill-switch: FopraLock2023
  • Ransom note filename: HOW TO DECRYPT FILES.txt
  • C2 Callback (Stage-2 download): hxxps://files-fopra[.]top/dl/fop.dat (taken down, sink-holed)
  • Session ID for support: 05860c4c9ccaa64a0b0a9b3bb7ec71a93b4bf6df9ef0c6e8b3325e2e5c3ba5d580

Stay patched, stay backed-up, and never trust a process that was not there yesterday. Good luck defending your data!