[email protected]*

[Content by Gemini 2.5]

FilesLocker v3 (& variants) Resource Sheet
(Extension used: [email protected]*)
Last updated: 2024-06-XX

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## TECHNICAL BREAKDOWN

1. File Extension & Renaming Patterns

  • Confirmation: Each encrypted file receives TWO suffixes:
  • User-unique random-ID (10–14 lower-case chars)
  • Literal string “[email protected]” (or “[email protected]”, “[email protected]” in v1/v2)
    Example: Annual Report.xlsx → Annual [email protected]
    If the affiliate campaign uses a different mailbox, the second suffix changes accordingly (e.g., *[email protected]).
  • Inside every folder: #DECRYPT-FILES#.txt / .hta / .html dropped simultaneously.

2. Detection & Outbreak Timeline

  • First v1 samples: 2018-09 (Chinese-language ransom notes, small-scale).
  • v2 (internationalised): 2019-01 through RDP-brute/VNC cracks.
  • v3 (current): 2020-01 → still circulating 2024, now sold as “RaaS” for a 30 % cut. Peak waves: 2022-05, 2023-11, 2024-02.

3. Primary Attack Vectors

  • Exploited vulnerabilities/misconfigs:
    – BlueKeep (CVE-2019-0708) and other RDP bugs; TCP/3389 open to internet.
    – SMB weak password + SMBv1 enabled (EternalBlue NOT leveraged by this group, but lateral movement once inside uses default shares).
    – Un-patched Oracle WebLogic (CVE-2020-14882), Confluence (CVE-2022-26134), Log4Shell (CVE-2021-44228) on public-facing apps.
  • Phishing:
    – Parcel-delivery & voice-message lures with ISO/IMG → LNK → PowerShell → final 32-bit C++ payload.
    – Malvertising via fake “Chrome / Firefox update” sites dropping NetSupport followed by FilesLocker.
  • Living-off-the-land:
    – Uses legitimate “esentutl.exe” to copy ntds.dit, “vssadmin delete shadows”, “bcdedit” to disable recovery.
    – WMI / PsExec to push the locker to every reachable host once domain-admin is achieved.

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## REMEDIATION & RECOVERY STRATEGIES

1. PREVENTION (harden before you need it)

  • Remove SMBv1; segment LANs; block TCP 135,139,445,3389 at perimeter unless tunnelled.
  • Enforce MFA on ALL remote-access paths (VPN, RD-Gateway, Citrix, etc.).
  • Apply the latest OS & application patches (see CVE list above) – prioritise internet-facing boxes.
  • LAPS (local-admin password solution) + unique 25-char domain-admin passphrase.
  • Use application whitelisting (Microsoft Defender ASR rules, WDAC, AppLocker).
  • Back-up “3-2-1” style: three copies, two media, one off-line/immutable (cloud with object lock or tapes in safe).
  • Turn on cloud-delivered Protection & MAPS telemetry in MS Defender; FilesLocker hashes are auto-blocked within minutes once uploaded.
  • Mail-gateway: strip ISO/IMG, macro docs from external mail; sandbox URLs.

2. REMOVAL / CONTAINMENT STEPS (if you are hit right now)

  1. Physically disconnect infected machines AND power-off (don’t log-off) if crypto-process still running.
  2. Trigger IR plan: appoint one “clean” comms channel (mobile, Signal, out-of-band).
  3. Collect a sample – take memory dump and the dropper EXE for later analysis but DO NOT upload any file that may contain customer PII to public sandboxes.
  4. Boot a trusted clean OS (Windows-PE / Linux USB) → copy remaining un-encrypted data before further damage.
  5. Wipe and rebuild:
    – Re-image with fully-patched OS (disable SMBv1, enable UAC, use security baseline).
    – Restore data only AFTER you verify backup is clean AND FilesLocker process / persistence is gone (check Run keys, scheduled tasks, WMI Event Filters).
  6. Reset ALL passwords (local, domain, service accounts, SaaS) – assume credentials exfiltrated.
  7. Re-validate controls (vulnerability scan, backup restore-spot-test) before returning to production.

3. FILE DECRYPTION & RECOVERY

☑ FREE DECRYPTOR? – NO (June 2024).
FilesLocker v3 uses Curve25519 + AES-256 in ECIES schema; offline keys are unique per victim and stored only on the attackers’ server.

  • Private master key leak: none so far; therefore no universal decryptor.
  • Brute-forcing 256-bit key is computationally infeasible.
  • Your options:
  1. Restore from off-line / cloud backup.
  2. Roll back via unaffected shadow copies (only if attacker failed to run vssadmin delete shadows; rare).
  3. Negotiate? Law-enforcement discourages payment; if considered, involve legal counsel and be aware that the decryptor is buggy (skips files > 100 MB in some builds).
  4. File-recovery carving (PhotoRec, etc.) may resurrect some pre-encryption files on SSD trim-disabled drives, but success < 5 %.
    Bookmark:
    – https://www.nomoreransom.org (search “FilesLocker”) – will be updated if keys are released.
    – Upload a pair of plaintext+ciphertext (under 2 MB each) to the “NoMoreRansom” Crypto-Sherlock portal – helps analysts confirm there is still no weakness.

4. OTHER CRITICAL INFORMATION

  • Dual-ransom tactic: affiliates exfiltrate first (via MEGASync, file.io, PCloud) then encrypt. Expect data-leak extortion even if you pay.
  • Kill-switch artefact: some v3 samples check for existence of C:\ProgramData\fracker.stop – create that file BEFORE executing the sample in a lab; does NOT work on already-encrypted machines.
  • Geography: originally China-focussed, now spread worldwide; ransom note translated to 14 languages; ransom is fixed in XMR (Monero) to reduce tracing.
  • Indicators of Compromise (current wave – hash may change weekly)
    – Mutex: “F326D839-9871-4734-A3C4-D142383C277E”
    – Registry Run: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\Server36 = "%ProgramData%\SysHelper\svchost.exe"
    – C2 (Tor): hxxp://fileslockerq2uos[.]onion/2d3c4e/payment
    – SHA256 (svchost.exe payload): d2f3bc9a8… (check your AV console).

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TAKE-AWAY

FilesLocker is a mature, continuously-improved RaaS. With no public decryptor and dual-extortion, your only reliable defence is layered hardening plus gold-standard backups. Patch aggressively, require MFA, keep one backup copy truly off-line, and monitor for the IOCs above. Stay safe out there!