dati*

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The ransomware appends .dati (exactly four lower-case characters) to every encrypted file.
  • Renaming Convention:
    Original: Quarterly_Report.xlsx
    After encryption: Quarterly_Report.xlsx.dati
    There is no affixed victim-ID or email address in the file-name, which distinguishes .dati from many earlier variants.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First public sightings and upload to malware repositories occurred around mid-February 2024.
  • Peak Activity: Spikes in telemetry were recorded in March-April 2024, coinciding with mass-planted malicious torrents (software “cracks”) and a malvertising campaign that redirected Windows users to exploit kits.

3. Primary Attack Vectors

| Vector | Details | Mitigation Take-away |
|—|—|—|
| Malicious torrents / warez cracks | Installers masquerading as keygens for software suites drop the loader. | Block P2P traffic at the perimeter, educate users on software supply-chain trust. |
| Exploit kit (RIG-v 2024a) | Drive-by download attempts in browsers running unpatched Chromium or Edge (<118). | Keep browsers fully patched, disable/disable Flash/PDF in browsers, use Ad-blocking DNS. |
| RDP brute-force & “credential stuffing” | A secondary module scans for open port 3389 and attempts common password lists. | Force NLA, strong unique passwords, MFA, IP-restrict inbound RDP. |
| SMBv1 (EternalBlue derivative) | A reduced port of the old exploit still successfully hits legacy Windows 7 / Server 2008 boxes. | Disable SMBv1, apply MS17-010 once—yes, still! |
| Phishing ZIP attachments | JS droppers hidden inside .iso inside .zip flagged by only 3 AV engines on submission day. | Strip .iso, .js, .wsf at mail gateway; S/MIME or SPF/DKIM enforcement.

Remediation & Recovery Strategies:

1. Prevention

  • Disable or remove SMBv1 on all servers and workstations via GPO (Disable-WindowsOptionalFeature –Online –FeatureName "SMB1Protocol").
  • Patch (or replace) anything older than Windows 10 build 19041 and Server 2012 R2 (or apply ESUs where feasible).
  • Implement strict RDP hardening: NLA + MFA (Microsoft Entra, Duo, etc.) and lock-out policies.
  • Use EDR/NGAV in “block” mode for PowerShell, JavaScript, MSHTA and WScript child-processes.
  • Enforce application control (WDAC/AppLocker signed-only rules).
  • Create 3-2-1 backups: 3 copies, 2 media, 1 offline/off-domain—critical against .dati, which deletes Volume Shadow Copies (vssadmin delete shadows /all /quiet) and also looks for NAS shares named in DFS lists.

2. Removal

  1. Isolate infected host(s): physically disconnect NIC or disable Wi-Fi.
  2. Boot into Safe Mode with Networking from a cold-start (avoid hibernation file artifacts).
  3. Scan offline: Run a freshly-updated AV/EDR rescue disk (Kaspersky KVRT, Bitdefender BD Rescue, or the Microsoft Defender Offline image).
  4. Purge persistence:
  • Delete scheduled tasks in C:\Windows\System32\Tasks\*System Update or dllhostup tasks.
  • Clean registry autostart keys under HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run for randomly-named binaries.
  • Remove any newly-created services (usually 8-char lowercase, e.g., ksmserv).
  1. Verify by rebooting into Windows normally and performing a second cross-vendor scan to be sure.
  2. Re-image if time-budget allows— .dati is known to patch lsass or leave open back-doors in certain loader versions.

3. File Decryption & Recovery

  • Decryption Feasibility (June 2024): No publicly available decryptor yet; the malware uses ChaCha20-Poly1305 keyed with an RSA-4096-encrypted session key, stored in a blob prepended to every encrypted file.
  • What you can try:
  • Preserve a copy of the encrypted data in case a victim-paid master key leak surfaces (follow @emsisoft, @AV_Sig).
  • Before wiping the machine: look for any plaintext** under %APPDATA%\Roaming or in the RAM dump—some early .dati builds accidentally dropped the ChaCha key in mapped memory.
  • Shadow-copy recovery is usually gutted, but in certain corporate backups you may find VSS left on Windows 2019 or 2022 servers if permission ACLs protected them.
  • Tools to have ready:
  • Emsisoft’s BL Ransomware Decryptor (watch for .dati prefix entry in changelog).
  • UPX-unpacked sample unpacking script (upx -d) when analysts need to extract the offline RSA public key for researchers.
  • Emergency script (check-published-keys.ps1) from GitHub gist (T. Gilles) that monitors the NoMoreRansom site feeds.

4. Other Critical Information

  • Network-Wide Kill Chain Signature:
  • Features a hard-coded C2 domain: datigw[.]eu[.]org (sink-holed as of 2024-03-27).
  • Drops run key:HKLM\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Run\WinDllSvc = "%Public%\system32\gdiplus32.exe" → verify this filename under newer incidents for hunting SIEM rules.
  • Ransom Note Filename & Coercion Style: Note file name: Read_Me_Recover_Files.txt.
    – No live chat; only protonmail address ([email protected]).
    – Pretends to be “Doxing” actors, but no evidence of data theft to-date—focus remains on encryption-for-ransom.
  • Broader Impact:
  • Has hit at least 40+ small manufacturing and engineering firms that still run legacy CAD workstations (Windows 7 + SMB1).
  • Typical ransom ask: 0.35 BTC (~USD 24 k as of April-2024), with 72-hour deadline; failure to pay leads to the email being deactivated by the same threat group.

Defensive One-Pager (sticker for SOC team)

  1. Patch ≥ Win10 22H2, kill SMBv1
  2. MFA every RDP endpoint
  3. 3-2-1 offline backups with daily password-protected ZIP-if-needed NAS copy
  4. Block .js , .iso inside email attachments outright
  5. Monitor for outbound Cobalt Strike or datigw DNS queries

Together, these steps hammer down every lever .dati currently uses, while the community waits for a possible future universal decryptor.