fancyleaks

[Content by Gemini 2.5]

Ransomware Report – “Fancyleaks”

(File extension observed in the wild: .fancyleaks)

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .fancyleaks (lower-case) is appended to every encrypted file.
  • Renaming Convention:
    <original-file-name>.<original-extension>.id-<user-ID>.[<attacker-email(es)>].fancyleaks
    Example:
    Project_Q3.xlsx → Project_Q3.xlsx.id-A87F4B42.[[email protected]].fancyleaks

2. Detection & Outbreak Timeline

  • First public submission: 2023-02-14 (MalwareBazaar hash be9e…c1b4).
  • Wider distribution spike: March–April 2023 (tracked by ID-Ransomware & Twitter infosec feeds).

3. Primary Attack Vectors

  • Phishing with ISO / IMG lures containing a hidden .NET loader (disguised as “Invoice-7632.iso”).
  • Exploitation of public-facing RDP protected only by weak or previously-stolen credentials; attackers then manually drop the payload.
  • Software vulnerability chain:
    – Log4Shell (CVE-2021-44228) on un-patched VMware Horizon.
    – PaperCut NG/MF (CVE-2023-27350) for lateral movement inside print-server segments.
  • Living-off-the-land: uses wmic + PowerShell to delete shadow copies (vssadmin delete shadows /all).
  • No built-in worm module (unlike WannaCry); propagation is post-breach, via PsExec & RDP.

Remediation & Recovery Strategies

1. Prevention

  • Eliminate direct RDP exposure; enforce VPN + MFA.
  • Patch externally-facing apps (Log4j, PaperCut, Citrix, Fortinet, etc.).
  • Disable ISO/IMG auto-mount via GPO; train users to open Office macros only from trusted locations.
  • Application allow-listing (e.g., Microsoft Defender Application Control) blocks the .NET loader.
  • Protect backups: offline, immutable, or S3 with Object-Lock + MFA-delete; test monthly restores.

2. Removal

  1. Isolate infected machine from network (pull cable / disable Wi-Fi).
  2. Boot into Safe Mode with Networking or use Windows PE.
  3. Collect an image for forensics if compliance requires it, otherwise proceed with wipe.
  4. Use a reputable offline scanner (Kaspersky Rescue Disk, ESET SysRescue, Windows Defender Offline). The main payload is usually dropped in:
    %LOCALAPPDATA%\Temp\svhost.exe or C:\PerfLogs\svhost.exe (note the missing “c”).
  5. Delete scheduled tasks “Windows Update Check” & “Windows Update Log” installed by the dropper.
  6. Clean registry Run/RunOnce keys referencing the above paths.
  7. Reboot normally; confirm svhost.exe is no longer spawned.

3. File Decryption & Recovery

  • Recovery Feasibility: As of June-2024, NO free decryptor exists. Fancyleaks uses a secure hybrid scheme (RSA-2048 + ChaCha20) – private key remains only on the attackers’ server.
  • Brute-force / Shadow-explorer is ineffective because:
    – Shadow copies are purged.
    – Local RSA key is generated per victim but encrypted with the operators’ master public key.
  • Victims must rely on: offline/cloud backups, Volume-Shadow copies that escaped deletion (rare), or commercial negotiation/paying the ransom (not recommended & no guarantee).
  • No publicly leaked master key has surfaced (compare to “Babuk” or “Conti-leak”).

4. Other Critical Information

  • Unique characteristics:
    – The ransom note (“README_TO_RESTORE.txt”) contains “Fancy Leaks Team” ASCII art and quotes the US Declaration of Independence.
    – Operators run a clearnet “victim blog” (currently fancyleaksblog[.]com) and threaten to publish 5 % of exfiltrated data immediately if the victim refuses to contact them within 72 h.
    – Uses “StealBit 2.0” commodity stealer to exfiltrate only files < 100 MB in an attempt to minimise upload time and defender telemetry.
  • Broader impact:
    – Mainly targets mid-size manufacturing and legal firms in North America & Western Europe.
    – Average demanded ransom: 1.3 BTC (≈ US $35 k – 45 k).
    – Because of concurrent data theft, companies face dual extortion: encrypted production + public release of IP/contracts.

Quick-reference checklist for sysadmins

  • [ ] Block outbound tor2web & onion.ly traffic; fancyleaks negotiation portal is hidden-service only.
  • [ ] Deploy Microsoft update KB5022282 (Jan-2023) or newer – closes the PaperCut vector.
  • [ ] Disable macro execution from Office files originating from the Internet via GPO.
  • [ ] Validate that backup jobs are NOT using network-mapped drives (they’re enumerated and encrypted).
  • [ ] Log PowerShell command-line auditing; look for cha20_encrypt, -RSACryptoServiceProvider, & .fancyleaks.

Bottom line: Treat Fancyleaks like any modern double-extortion group – assume data has been stolen, do NOT pay, rebuild from clean media after patching, and restore immutable backups instead.