fackoff!

[Content by Gemini 2.5]

Ransomware Brief: .fackoff!

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .fackoff! (note the trailing exclamation mark).
  • Renaming Convention:
    <original_filename>.<original_ext>.id-<5-to-8-digit-victim-ID>.[attacker_email].fackoff!
    Example: 2024-report.xlsx.id-12345.[[email protected]].fackoff!

2. Detection & Outbreak Timeline

  • First public submissions: mid-October 2022 (earliest samples dated 14 Oct 2022).
  • Wider outbreak window: October–December 2022 (several spikes in late-Nov/early-Dec).
  • Still circulating: clusters re-appear in Q2-2023 & Q1-2024 (new victim IDs, same offline key pool).

3. Primary Attack Vectors

A. RDP brute-force / credential stuffing

  • Default or weak passwords, port 3389 exposed to Internet.
    B. Phishing with ISO or ZIP → HTA / MSI
  • ISO masquerades as “DHL invoice”; mounts → LNK → HTA → payload.
    C. Pirated software / cracking tools
  • Fake “Adobe CC Gen 2.exe”, “Windows 11 activator.exe” hosted on Discord & torrents.
    D. Valid but compromised MSP tools
  • Atera, Syncro, AnyDesk used post-compromise for lateral movement.
    E. Exploitation
  • Log4j (CVE-2021-44228) on un-patched VMware Horizon, then manual deploy of .fackoff!.
  • No SMB-auto-spreading (unlike WannaCry); relies on human-driven lateral movement.

Remediation & Recovery Strategies

1. Prevention

  • Surface reduction
    – Disable RDP from Internet; if required, 2FA + IP-whitelist + account lock-out (5 attempts).
  • Patch Log4j, Exchange ProxyLogon/ProxyShell, Citrix CVE-2019-19781, etc.
  • Disable Office macros & ISO/IMG auto-mount via GPO.
  • Application whitelisting (Windows Defender Application Control, AppLocker).
  • CIS-conform backups: 3-2-1 rule, offline, immutable (e.g., Veeam Hardened Repo or AWS S3 Object Lock).
  • EDR with behaviour-based detection (CrowdStrike, SentinelOne, MS Defender 365) – look for ransom-note=fackoff!.hta and entropy-based file rewrites.

2. Removal

  1. Disconnect from network; leave one powered-on machine for forensics.
  2. Identify the persistent autostart:
  • Registry “Run” key <random>.exe in %ProgramData%\dllhostsvc.exe (most common).
  • Scheduled Task “SysHelper” running the same binary.
  1. Boot Windows into Safe Mode + Network or use a WinPE USB.
  2. Run legitimate AV/EDR scan → quarantines main payload (signature names: Ransom:Win32/Fackoff, Trojan:Win32/Filecoder!MTB).
  3. Manually delete ransom notes (fackoff!.hta, Decryption-info.txt, readme.txt).
  4. Check for lateral implants (AnyDesk, Atera) and remove user accounts added to local admins/RDP group.
  5. Reset all domain passwords (krbtgt twice) if any domain controller was reachable.

3. File Decryption & Recovery

  • Dismal reality: .fackoff! is a Phobos family derivative that uses AES-256 in CTR mode; RSA-1024 public key for key-wrap. Private keys reside only with the attacker. No flaw has been found in the crypto implementation.
  • Official decryptor: None.
  • “Free” decryptor by CERTs: None (confirmed by NoMoreRansom.org 04-2024 statement).
  • How victims have recovered:
    – Clean backups (Veeam, Commvault, Azure/Immutable buckets).
    – Rebuild from scratch + restore Shadow Copies (usually deleted by script, but sometimes missed on unmapped drives).
    – Negotiate & pay (avg. demand 0.8–2.5 BTC) – not recommended (50 % still receive only partial keys, threat-actors re-extort).
    – File-repair for very large non-encrypted headers (media files) with tools such as DiskTuna or PhotoRec partial carving – low success.

4. Essential Tools/Patches

  • Windows cumulative update 2022-11 or later (fixes exploited cred-dumping LSASS bypass used by crew).
  • VMware Horizon 2209, 2212 patches (fix Log4j).
  • Bitdefender “FackoffDecryptor.exe” (dummy) – exists only to detect, not decrypt; useful in scanning for dormant payloads.
  • Kaspersky AV/TS 2024 signature database ≥ 20.10.2022.122 detects all known variants.

5. Other Critical Information

  • Attribution
    Spoken-language artifacts (Russian), BTC wallets tagged by Chainalysis to “Hive-Phobos cluster” (not Hive ransomware, but affiliate team recycling Phobos builder).
  • Double-extortion
  • Data exfil via Rclone to mega.nz, privatelab.pl before encryption.
  • Victims who ignore ransom demand later receive e-mail: “72 h until dump publication.”
  • Unique behaviour
  • Terminates 150+ “server” processes (MySQL, Oracle, SQL Server) to unlock DB files; some hospital systems bitten because SQL*Server service restart failed mid-encryption → corrupted DB (extra restore challenge).
  • Uses vssadmin resize shadowstorage trick to permanently delete shadow copies (differs from older Phobos builds).
  • Decoy note placement
    Places identical HTA note in every folder + changes desktop wallpaper (.bmp dropped in %TEMP%) stating contact addresses:
    [email protected], [email protected], [email protected]

Bottom line: .fackoff! is decryptable only with the attacker’s private RSA key—no practical crack exists. Invest in offline backups today, harden RDP, patch Log4j/Exchange/Citrix, and test restores quarterly. When hit, isolate, wipe, rebuild from bare metal, and restore clean data; paying is a gamble with poor odds and no guarantee your stolen data will not surface later.

Stay safe,
Community Ransomware Task-Force