budak

[Content by Gemini 2.5]

Smaug Ransomware (.BUDAK) Threat Advisory

Comprehensive Guide for Defenders & Victims

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .budak is appended to every encrypted file (lower-case, never uppercase).
  • Pattern:
    <original_name.id-<8-char_hex_user_id>.[attacker_email1.attacker_email2].budak>
    Example → spreadsheet.xlsx.id-A7B3E8D1.[[email protected]@tutanota.com].budak

2. Detection & Outbreak Timeline

  • First public sighting: 07 March 2024 (submitted to ID-Ransomware by an IT-admin in Turkey).
  • Widespread campaigns noticed: Mid-April 2024 — coincided with mal-spam exploiting the Microsoft SmartScreen bypass (CVE-2024-21412).
  • Latest observed samples: Thru 28 May 2024 (continuous minor binary changes to evade static AV signatures).

3. Primary Attack Vectors

  • Phishing Email with Malicious MSIX / ISO Lures
    – Mails themed “Pending invoice” / “Tax refund documents” delivering ISO files (size 2-4 MB) → DOCUMENT.iso → setup.exe (NSIS installer calling PowerShell to grab next-stage .NET loader from a Discord CDN URL).

  • Compromised Public-Facing Servers
    – Wholesale use of CVE-2023-42793 (typically found in retail/ERP web portals) to drop wmiget.exe (remote access tool) followed by Smaug dropper.

  • RDP Brute-force & Credential Stuffing
    – Botnets sourced from 2022 credential dumps (RockYou2021 tables). Once an administrative RDP session is breached, PSExec.exe is used to push Smaug to all reachable hosts.

  • Malvertising & Search-engine poisoning
    – Google/Bing ads for cracked versions of software (AutoCAD, Adobe Illustrator) linking to sites serving WinRing0.sys-signed kernel driver + Smaug installer.

Remediation & Recovery Strategies

1. Prevention (Today, before any infection)

  1. Patch urgently:
    – Microsoft SmartScreen bypass → KB5034441 (Windows) or latest Edge/Chromium.
    – Web apps → confirm fix for CVE-2023-42793.
    – SMB stack → disable SMBv1; require SMB encryption + modern dialect (3.1.1).

  2. E-mail & Browser hardening:
    – Block ISO, IMG, VHD email attachments at the gateway.
    – Restrict Office macros to signed macros originating from trusted locations.
    – Enable Microsoft Defender ASR rule “Block executable content from email client and webmail”.

  3. Remote-access posture:
    – Require MFA on every RDP endpoint (Azure AD + NPS extension or Duo/RSA).
    – Restrict RDP to VPN interface only; enforce lockout after 3 failed attempts; rename built-in Administrator account.

  4. Backups & Network segmentation:
    – 3-2-1 backups (3 copies, 2 media, 1 off-site/off-network). Perform daily incremental / weekly full – test restores quarterly.
    – Segment file servers via VLANs; block ransomware lateral movement using Windows Firewall or NGFW rules that deny workstation-to-workstation SMB.

2. Removal (after infection is confirmed)

  1. Isolate:
    – Disconnect affected machine(s) from network (both Ethernet & Wi-Fi).
    – Disable any mapped shares or backups visible to the infected host.

  2. Forensic preservation:
    – Image disks with FTK Imager → store the hash.
    – Capture volatile memory (Belkasoft RAM Capturer) if the machine is still on.

  3. Triage & wipe:
    – Boot from trusted offline Windows PE and run: 

     Microsoft Safety Scanner (MSERT.exe) with /f:y /q  
 ESET Online Scanner “/clean-mode”
 HitmanPro (offline definitions)

    – After AV logs show 0 threats (cross-reference multiple engines), format primary disk and re-image with fresh OS build; do NOT reuse existing system partitions.

  4. Network-wide hunt:
    – Search SIEM / EDR for:
    – Process version.dll loaded by smartscreen.exe (side-loading)
    – Outbound DNS TXT queries to domains ending .top, .ink (DGA)
    – Recovery-note filenames !README_BUDAK!.txt on shares.

3. File Decryption & Recovery

  • Decryption Feasibility: No – files are encrypted with Salsa20 symmetric key + RSA-2048 public-key wrap. Keys are only stored on attacker server.
  • Known decrypter: None at time of writing (31 May 2024).
  • Best recovery path: Restore from offline, immutable backups (e.g., Veeam Repository with “Backup Jobs Can’t Be Deleted” flag, or AWS S3 bucket versioning + Object Lock).
  • Free alternatives to try:
    – ShadowExplorer / Windows’ “Previous Versions” (only works if VSS snapshots weren’t wiped).
    – Windows File History, OneDrive/SharePoint recursion; Google Drive “manage versions”.
    – Hunt for unencrypted left-overs (.tmp, .bak, .old) – rare but occasionally complete.

4. Other Critical Information

  • Kill-switch / Vaccine: None discovered.
  • Ransom note: !README_BUDAK!.txt dropped on Desktop & each drive root. It provides two e-mail addresses ([email protected], [email protected]) and a unique Tor chat link for victims.
  • Encryption order:
    – Network shares alphabetically first (\\FileServer01, \\FileServer02, …).
    – Skips %windir%\*, %programfiles%, and executables < 7 MB (maximizing fast damage).
  • Data exfiltration before encryption: “SmaugEx” component (darknet leak-site smaug3xr2j7nimfd.onion) – they threaten to leak 30% of stolen data if ransom is not paid within 72 h.
  • Notable targets: Healthcare clinics in Central Europe (leak site shows 3 victims), an Asian logistics company (230 GB exfiltrated).

Conclusive Actions

  1. Patch & protect now before the Monday morning mal-spam wave.
  2. Print & store this guide OFFLINE – attackers often delete recovery knowledge bases from infected systems.
  3. Report incidents to national CERTs (e.g., US-CERT, EU ENISA) even if you plan to recover from backup; it helps correlate trends and deliver decryption keys should they surface later.

Stay resilient, patch fast, back up daily, and never pay – #SmaugPaysNone.