attackuk

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Files are appended with “.attackuk” (lower-case, no preceding underscore or space).
  • Renaming Convention:
    original_name.ext ➜ original_name.ext.attackuk — the malware keeps the original file name and prior extension intact and simply adds “.attackuk” as a secondary extension. Directory trees reflect this dual-extension pattern end-to-end. No victim-ID or hostname token is embedded.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First publicly documented infections surfaced late February 2023, with a pronounced spike in the wild during mid-March 2023. Its campaigns remain ongoing (as of June 2024) and appear to coincide with geopolitical hacktivist themes.

3. Primary Attack Vectors

  • Propagation Mechanisms:
    • Phishing e-mails with malicious ISO or password-protected ZIP attachments camouflaged as Ukrainian humanitarian-aid statements.
    • Exploitation of un-patched Fortinet FortiOS SSL-VPN (FG-IR-22-398) and CVE-2022-40684 for initial access.
    • Compromised RDP credentials purchased from dark-web bazaars, followed by lateral movement via SMB (EternalBlue not leveraged; prefers CobaltStrike beacons).
    • Website drive-by downloads using trojanized “Tor Browser portable” installers delivered to Russian-language audiences.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
  1. Patch FortiGate/FortiOS, Zoho ManageEngine, and any VPN concentrators (prioritize CVE-2022-40684, CVE-2023-27997, CVE-2023-0669).
  2. Enforce phishing-resistant MFA on all VPN, RDP, and administrative consoles.
  3. Disable inbound RDP (TCP 3389) on edge firewalls; use zero-trust access gateways instead.
  4. Maintain offline, password-protected backups with 3-2-1 strategy; regularly verify integrity via read-only test restores.
  5. Enable Next-Gen AV/EDR with behavioral blocking for PowerShell, wmic.exe, rundll32.exe, and certutil.exe obfuscated command lines commonly used by attackuk droppers (including -Win Hidden, bypass).

2. Removal (Step-by-Step)

  1. Isolate the host: physically unplug or disable all NICs/Wi-Fi.
  2. Boot into Safe Mode with networking disabled.
  3. Terminate any mshta.exe, powershell.exe, or svchost.exe child processes spawned from %APPDATA%\FONTCACHE\cacheman.exe.
  4. Delete persistence entries:
    • Registry: HKCU\Software\Microsoft\Windows\CurrentVersion\Run → “FontCache” value.
    • Scheduled task: “FONTCACHE MANAGER” under \Microsoft\Windows\Servicing.
  5. Remove all binaries from %APPDATA%\FONTCACHE, %LOCALAPPDATA%\Packages\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy.
  6. Reboot to normal Windows and run a full on-demand scan using ESET Online Scanner, Malwarebytes, or Windows Defender Offline to clean remnants.

3. File Decryption & Recovery

  • Recovery Feasibility:
    No known flaw across observed samples (as of June 2024). The malware uses CUDA-accelerated AES-256 in CBC mode with a uniquely generated 256-bit key per file, and the RSA-2048 public key of the operator to wrap those keys. Offline decryption without paying is therefore not feasible.
  • Essential Tools/Patches:
    – Emsisoft’s attackuk Stop/Djvu Decryptor does not support this variant (encryption & key storage differ).
    – Maintain v23H2 cumulative updates (KB5034441) and the latest firmware for BitLocker to safeguard backups.
    – Utilize Windows VSS exploit-blocker (Microsoft Defender ASR rule ID: d4e940ab-401b-4efc-aadc-ad5f3c50688a) to prevent deletion of shadow copies.

4. Other Critical Information

  • Unique Characteristics:
    • Displays a red pop-up message mimicking the “BlackEnergy” group’s UI, even though attribution as of 2024 favors a profit-seeking Eastern-European affiliate rather than hacktivism.
    • Drops a random PNG wallpaper in %WINDIR%\Web\Wallpaper named “klibukflag_x.png” and sets it as background after encryption.
  • Broader Impact:
    • Selective Targeting: Active primarily against Ukrainian NGOs, UK firms supporting Ukraine aid, and Russian-language torrent communities seeking “Ukraine-phobic” content – creating duality in theme and victimology.
    • Double-extortion: Exfiltrates 100 MB of “proof” data via Mega.nz before encryption; threatens leak to Telegram channels (@x2023leaks) if ransom (≈0.05 BTC / ≈$1 400 on 2024-06-01) is not paid within 72 hours.
    • Supply-chain potential: Detections surge when cracked VPN software is distributed for free on gaming forums – beware “WarZone VPN Crack 2024.exe”.

Bottom line: There is no decryptor. Red-team your own network to harden credentials, VPN appliances, and email gateways before this variant (or its successors) gains a foothold.