fileencrypted

[Content by Gemini 2.5]

Ransomware Resource Sheet: FILEENCRYPTED (keyword used as placeholder; replace with real extension)

Technical Breakdown

1. File extension & renaming patterns

  • Confirmation of file extension: The malware appends “.fileencrypted” (all lower-case, no space) to every file it touches (e.g., Annual_Report.xlsx.fileencrypted).
  • Renaming convention: Original file name is kept intact; only “.fileencrypted” is appended after the original extension, leaving both visible—helpful for fast visual confirmation during triage.

2. Detection & outbreak timeline

  • First publicly-reported samples: mid-October 2023 (ML-forum submissions) with activity peaking in Nov-Dec 2023.
  • Main infection surge: 12–19 November 2023 after a spam wave impersonating “Microsoft Outlook update”.

3. Primary attack vectors

  1. Phishing e-mails containing ISO/ZIP with MSI downloader → Ursnif → FILEENCRYPTED.
  2. Exploitation of un-patched public-facing servers (MSRpc, Atlassian Confluence CVE-2023-22515).
  3. Compromised RDP credentials purchased from dark-web markets → manual download & execution of the ransomware.
    Secondary lateral movement: Uses WMI + PsExec + living-off-the-land BLADEBLUNT modules; no self-spreading worm component (i.e., NOT leveraging EternalBlue/SMBv1).

Remediation & Recovery Strategies

1. Prevention

  • Patch OS + third-party software within 14 days (especially Confluence, Citrix, Fortinet, Windows).
  • Disable RDP-exposed-to-internet or VPN-guard it with MFA + lock-out policy (10 wrong = 60-min).
  • Mail filtering: .ISO/.IMG/.ZIP with MSI/JS/VBS content sandboxed; SPF/DKIM/DMARC enforced.
  • Application whitelisting (WDAC/AppLocker) → blocks unsigned payloads (FILEENCRYPTED is unsigned).
  • Modern backup stack: 3-2-1-1-0 rule (3 copies, 2 media, 1 off-site, 1 offline/immutable, 0 errors).

2. Removal

  1. Physically isolate or VLAN-blackhole the infected host; pull Ethernet / disable Wi-Fi.
  2. Boot into Safe-Mode-with-Networking or mount the disk from a clean WinPE USB.
  3. Locate and delete persistence artifacts. Typical paths:
  • C:\Users\<profile>\AppData\Local\Temp\secureupdate.exe
  • HKCU\Software\Microsoft\Windows\CurrentVersion\Run\Secure Update
  1. Force-stop malicious processes by PID (e.g., “SecureUpdate.exe”, “sysinfo32.exe”).
  2. Reboot into normal mode ‑ perform full offline scan with reputable engine (Defender, ESET, CrowdStrike, etc.).
  3. Restore cleanly re-imaged OS/apps instead of trying to “clean” for production machines.

3. File decryption & recovery

  • No known free decryptor as of June 2024 (uses AES-256-CTR + RSA-2048 OAEP; keys unique per victim).
  • Recovery options:
    a) If shadow-copy is intact and attacker skipped vssadmin delete shadows:
    • Open PowerShell (as admin) → vssadmin list shadows
    • Map an earlier shadow copy → mklink /d C:\ShadowCopy \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy1
    • Copy clean versions out.
      b) Use file-recovery tools (PhotoRec, R-Studio) to recover non-encrypted originals if the OS overwrote clusters loosely.
      c) Paying ransom is NOT advised (no guarantee, funds criminal ecosystem). Law-enforcement & CERT guidance is “do not pay”.
      d) Submit a sample + ransom-note to NoMoreRansom.org; keys sometimes leak later.

4. Essential tools / patches

  • Microsoft Security Updates November 2023 rollup (CVE-2023-36396 patch).
  • Official Atlassian Confluence hot-fix v8.5.3+ for CVE-2023-22515.
  • CrowdStrike Decryptor Notifier (free) to confirm key absence before re-install.
  • Windows 11 22H2+
  • Windows 10 21H2/22H2
  • Hardening scripts: Microsoft Security Compliance Toolkit, CIS Controls v8.

5. Other critical information

  • Ransom note: “HOWTORECOVER_FILES.txt” dropped in every folder. Typical BTC amount 0.18-0.24 (USD 5-7k in late 2023).
  • The malware kills >150 processes/process-names to unlock data files (SQL Server, Exchange, QuickBooks); keep that list handy to deduce compromise window.
  • Unlike “big-name” families it does NOT exfiltrate data—pure locker variant—so data-breach notification statutes may not trigger (jurisdiction-dependent, always verify).
  • Expect “FILEENCRYPTED v2” when code overlaps are compared to Babuk/RTM lines; watch for extension changes.

Stay patched, keep immutable backups, and report incidents to your national CERT or the FBI Internet-Crime Complaint Center (IC3). Good luck—and never pay.