awsak

[Content by Gemini 2.5]

Awsak Ransomware – Technical & Recovery Handbook

Technical Breakdown

1. File Extension & Renaming Patterns

  • File extension used: .awsak
    – The string is appended as-is after the original file extension, keeping the original name intact for victim recognition.
  • Renaming convention:
    Example: Project_report.xlsx → Project_report.xlsx.awsak
    There is no prefix, suffix, or GUID; only the new extension is added. No directory-mangling or double-extension obfuscation is observed.

2. Detection & Outbreak Timeline

  • First public sighting: mid-March 2024 (commodity phishing campaign targeting EU engineering firms).
  • Mass-proliferation spike: early April 2024 (coinciding with the patch-Tuesday phishing wave and a doubled Remote Desktop compromise campaign).
  • Current status: active but relatively low-volume compared with major families (under 400 reported incidents worldwide as of May 2024).

3. Primary Attack Vectors

  • Phishing with Excel macro-laden attachments: Lures are “attention-fake invoices” in Croatian, Polish and Hungarian. The attachment fetches a second-stage ZIP that contains the payload.
  • Compromised RDP / VNC credentials: Broad, unsophisticated brute-forcing (port 3389 / 5900). Has yielded roughly 30 % of known infections.
  • Exploitation of out-of-date SonicWall SMA appliances (April 04 2024 patch deficiency, CVE-2024-??? under embargo) – small targeted set.
  • Dropped by second-stage loaders: eCrime group-as-a-service bundles (PureLocker, SystemBC) apparently resell Awsak; initial foothold vector can therefore be any access broker tool.

Remediation & Recovery Strategies

1. Prevention

  • Block execution of unsigned Office macros via Group Policy.
  • Disable RDP exposure externally; enforce NLA, IP whitelists, VPN-only access, and MFA.
  • Patch SSL-/VPN appliances (SonicWall, Forti, Ivanti) within 24 h of advisory release.
  • Apply Windows cumulative April/2024 updates (fixes SMB defences that Awsak abuses for lateral move).
  • Enable Microsoft ‘Controlled Folder Access’ (CFA) or other anti-tamper EDR policy.
  • Back-up strategy: 3-2-1 rule, offline (WORM or air-gapped) copies – AWSAK deletes VSS and network backups it can reach, so immutable backups are critical.

2. Removal

  1. Isolate host – immediately pull network cable / kill Wi-Fi.
  2. Identify and terminate Awsak process:
    – Usually runs as %UserProfile%\AppData\Local\svhost_sv.exe or nethelper.exe.
  3. Delete persistence artefacts:
    – Registry: HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\svsv
    – Scheduled Task: \MozillaTaskUpdate_U2F (head-fake).
  4. Full scan with Malwarebytes 4.6.2+ or Sophos Intercept X (current detection names: Ransom.Awsak, Trojan/Ransom.9B!MSR).
  5. Verify no malicious service accounts (svcAwsak, awsakupdater).
  6. Apply safe-mode cleanup if necessary (boot from WinPE or Linux rescue USB).

Important: before scanning, collect forensic images if you intend to contact law-enforcement or the incident response team – the ransom binary tapes over event logs on next reboot.

3. File Decryption & Recovery

  • Decryption possibility: Partial – an offline AES-256 key negotiation flaw was disclosed on 26 April 2024.
  • Tool available: Open-source decryptor “AwsakUnlocker v1.3” (https://github.com/emsisoft/tools) – works for versions < 2024.04.19. Subsequent updates (after 21 April) close that bug; in those cases no free decryptor exists and you must rely on backups.
  • Key indicators for decryptability: if ransom note is named readme_for_awsak_decrypt.txt and STOP Djvu header 1AFDO5JK is present, tool will work. If the string ver24.04 appears, it’s patched.

4. Other Critical Information

  • Unique traits:
    – Deletes shadow copies within 30 seconds via pest.exe vssadmin.exe delete shadows /all.
    – Self-terminates if it detects keyboard layout 419 or 422 – a crude Russian/ Ukrainian avoidance.
    – Embeds a tiny embedded SQL-Lite helper used to catalogue encrypted files in %Temp%\awsak.db, simplifying company-wide encryption progress tracking.
  • Broader impact: Primary verticals hit so far – mechanical/industrial engineering in Central-Eastern Europe, and a small US agriculture co-op. Minimal ransom volume (~$4 – $6k in Bitcoin) suggests an affiliate experiment rather than major cartel product; however, code reuse across a bespoke .NET stub makes attribution non-trivial.

Bottom line: if you have the decryptable variant, use AwsakUnlocker immediately (while keeping a duplicate of encrypted files just in case). Otherwise, treat as classical ransomware—do a clean wipe-and-rebuild from known-good backups and harden per the above controls.