fopa

[Content by Gemini 2.5]

FOPA Ransomware – Community Defense & Recovery Guide

(Last updated: 2024-06)

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmed extension: .fopa (lowercase; appended directly after the original extension, e.g. invoice.docx → invoice.docx.fopa)
  • Renaming convention:
    – Keeps the original file name and first extension; simply concatenates .fopa
    – No e-mail, random hex string, or victim-ID prefix/suffix (differentiates it from variants such as Dharma/Phobos)

2. Detection & Outbreak Timeline

  • First public submissions: 2023-10-18 (ID-Ransomware, Malware-Bazaar, VirusTotal)
  • Peak activity: November 2023 – January 2024; still circulating in H1-2024 but at a lower volume

3. Primary Attack Vectors

FOPA is a STOP/Djvu offshoot; therefore, it copies that family’s usual distribution playbook:

  1. Pirated software & “cracks”: fake Adobe, Office, AutoCAD, game cheats, KMS activators delivered via:
  • Torrents (1337x, RARBG clones)
  • YouTube “how-to-crack” comment spam with bit.ly/GDrive links

  1. Pay-per-install (PPI) malvertising: redirect chains ending in .iso or .zip payload hosted on Discord, GitHub, or compromised WordPress.

  2. SmokeLoader follow-on: systems already infected with SmokeLoader/RedLine get FOPA as post-exploitation ransomware (smaller subset).

  3. No current in-the-wild exploitation of unpatched OS/services (differs from Conti/LockBit); MSP/RDP brute-force incidents are rare for this variant.

Remediation & Recovery Strategies

1. Prevention

  • Block/restrict execution of %LOCALAPPDATA%\*.exe & %TEMP%\*.exe with Microsoft Defender ASR rule “Block executable files from running unless they meet a prevalence, age, or trusted list criterion”.
  • Disable Windows Script Host if not required—most STOP/Djvu droppers use small .vbs/.js bootstrap.
  • Strict application whitelisting for common crack directories:
    – C:\Users\*\Downloads\*
    – C:\Users\*\AppData\Local\Temp\7z*, Rar*\*, ...
  • Patch, but note: FOPA does not leverage SMB/EternalBlue—focus endpoint budget on behavioral/AV rather than worrying about BlueKeep, etc.
  • Maintain offline (immutable) backups – 3-2-1 strategy. STOP/Djvu variants delete VSC with vssadmin delete shadows /all early in execution.

2. Removal

FOPA is well-detected; the pain point is encrypted data, not persistence.

Step-wise cleanup (choose your tooling – Windows 10/11):

  1. Physically disconnect from network (Wi-Fi off, Ethernet out).
  2. Power on with Windows Defender Offline or a reputable rescue disk (Kaspersky, ESET, Sophos) → full scan → quarantine:
    – Trojan:Win32/StopSvc
    – Trojan:Win32/StopMalware
    – Ransom:Win32/StopCrypt (Microsoft names)
  3. After reboot, run Malwarebytes or ESET Online Scanner to catch residual SmokeLoader modules.
  4. Inspect Scheduled Tasks & Run keys for random-name entries such as SysHelper, ServiceUpdate, Windows Defender Svc pointing to an .exe in %AppData%; remove manually or with Autoruns (verify signature = unsigned).
  5. Clear ISO/zip that brought the malware; nuke any “crack” folders to avoid re-infection.
  6. Only after forensic copy of encrypted data + removal logs, re-attach machine to LAN.

3. File Decryption & Recovery

Key point: STOP/Djvu variants AFTER August-2019 use online RSA-2048 keys; FOPA falls into that bucket.

  • Free decryptor (Michael Gillespie / Emsisoft) works ONLY:
    – If you have an “offline key” infection (ransom note mentions “personal ID ends with t1”)
    – Test quickly with the decryptor below.

Tool: Emsisoft_Decryptor_STOPDjvu.exe (sig: Emsisoft, updated 2024-05)
– Launch → “Yes, I have an offline key” → point to a pair of encrypted + original files (recover from backup or e-mail attachment) → decryptor fetches the offline key automatically.
Success rate with offline key ≈ 100%.

If your personal ID shown in _readme.txt DOES NOT end in “t1” → online key → not decryptable without the criminal’s private RSA key.
➔ Options then:
a. Restore from backup.
b. ShadowExplorer – but VSS almost always purged.
c. File-recovery tools (PhotoRec, R-Studio, Windows File Recovery) to carve non-encrypted copies the malware overwrote once; low success rate on SSD/TRIM systems.
d. Paying the ransom (currently $980 / $490 discount) is technically possible but: funds criminal ecosystem, no guarantee, violates OFAC if the group is sanctioned (Djvu/STOP actors overlap with sanctioned entities). Not recommended by law-enforcement.

4. Other Critical Information

  • Ransom note: _readme.txt (identical text template to all STOP/Djvu) – e-mails: [email protected], [email protected], later iterations may swap in [email protected] etc.
  • Dropped along: updatewin.exe (process hollowing to svchost.exe), 1.exe (blanker that wipes VSS, disables WD notifications), and sometimes 2.exe (RedLine stealer).
  • Network activity: hxxp://[:]//terca擒vity驭p托pics驭.com/* (GET /raqq/*/01.jpg, /03.jpg) – C2 beacon pattern; IP rotates via Cloudflare proxy.
  • ID change: FOPA moved from the 4-letter .fopa URL slug to 5-letter (.fopaa) in 2024-04 samples—still same master RSA key, decryptor works for offline t1 keys.
  • Broader impact: Because its distribution piggybacks on “free software” demand, home users/SMBs with casual IT policy are disproportionately affected; infection of a single employee laptop is often the seed for encrypting locally mapped server shares.

Share responsibly:

Stay patched, stay backed-up, stay away from “free” cracks – FOPA may be decryptable for “offline” victims, but good backups make even that gamble unnecessary.