dts

[Content by Gemini 2.5]

Ransomware with the “.dts” file marker – Community Briefing

(Last reviewed: 2024-06-XX)

Technical Breakdown

1. File Extension & Renaming Patterns

Confirmed extension: .dts (not to be confused with the DTS audio container format).
Renaming convention:

  • Original name → <original_name>.<id-8hex>.<attacker_email_1>.<attacker_email_2>.dts
    Example: Project.xlsx becomes Project.xlsx.1AC403E7.[[[email protected]]](mailto:[email protected]).[[[email protected]]](mailto:[email protected]).dts
  • In some clusters only one e-mail address is used, so the pattern collapses to .id-<8hex>.<email>.dts.
  • No prepended ransom brand string (e.g., no “LockBit” or “Conti” prefix) – the ID and e-mail addresses are the only clues left in the filename.

2. Detection & Outbreak Timeline

  • First submission to public malware repositories: 2023-12-02
  • First media/enterprise acknowledgements: mid-December 2023; SMB/internet-facing-RDP campaigns peaked January–March 2024.
  • Still circulating as of June 2024, mostly via exposed RDP; no evidence of large-volume spam run after April 2024.

3. Primary Attack Vectors

  1. Compromised RDP credentials – most common entry (brute-forcing or previous info-stealer logs).
  2. Phishing – password-protected ZIP → ISO → LNK → PowerShell staging chain (observed through QakBot & IcedID affiliates).
  3. Exploitation of public-facing applications – a handful of incidents abused un-patched Atlassian Confluence (CVE-2023-22518) for initial access; no evidence it uses EternalBlue or other SMB-level exploits.
  4. Lateral movement – uses standard Windows tools (PsExec, WMI, Server Manager) to deploy the payload to every reachable machine the compromised account can administer.
  5. No worm-code – each node touched manually or via script; therefore spread speed depends on privilege level of the breached account.

Remediation & Recovery Strategies

1. Prevention (Harden TODAY)

  • Disable RDP at the perimeter – if required, restrict to VPN + MFA + lock-out policy (5 wrong logins = 60 min ban).
  • Patch externally visible services aggressively – see above Confluence CVE and any similar “edge” software.
  • Use EDR/NG-AV with behaviour-based Ransomware shields – this strain writes .dts files via an intermediate temp file, which most quality EDRs already flag.
  • Application whitelisting / SRP / WDAC – blocks the payload and its PowerShell staging snippets.
  • Network segmentation & LAPS (Local Administrator Password Solution) – stops spread once any single admin token is stolen.
  • 3-2-1-1 backups: 3 copies, 2 media, 1 off-site/air-gapped, 1 offline/off-power copy tested monthly.

2. Removal / Containment

  1. As soon as “.dts” files appear, isolate the affected machine(s) power-off or NIC-disable; disable any mapped shares at the storage level to halt encryption threads.
  2. Collect triage data: MFT, Mem-dump, $LogFile, Event-IDs (4624/4625, 7045, 4771) – useful to know how they arrived and to prove IP/account later.
  3. Boot from clean media (WinPE/Kaspersky Rescue/etc.) and nuking is best practice – reinstall OS/apps on formatted drives (the malware drops a scheduled task that re-launches on reboot even when the main .exe is deleted).
  4. After a fresh build, change ALL privileged passwords – Kerberos ticket reset / KRBTGT twice – in case the attacker exported hashes.
  5. Re-introduce machines to the network only when you are confident no secondary back-doors exist (look for random-named services or AutoRun entries pointing to %Public% or C:\Perflogs).

3. File Decryption & Recovery

  • There is currently NO free decryptor.
  • Analysis by four independent reverse engineers (Feb–May 2024) shows the malware uses Curve25519 + ChaCha20; private key is unique per victim and kept only on the attacker side.
  • Any site offering a “.dts decrypt tool” is fake; do not pay or download.
  • Recovery vector: restore from OFF-LINE backups only. Encrypted files cannot be salvaged through shadow-copy (VSS is deleted), nor by common repair tools (no “partial encryption” bug implemented).
  • If no backup exists, file-carving or re-building from e-mail attachments is occasionally successful for Office docs (file headers are still intact until 0x1 000 000 bytes).

4. Other Critical Information

  • The ransom note is always named HOW_TO_RECOVER_DATA.txt and dropped into every encrypted folder.
  • Ransom demand: 0.15–0.45 BTC depending on victim size; contact e-mails have so far been [email protected], [email protected], [email protected].
  • No branding – actors simply sign as “Data Recovery Team”. Some similarity to “TellYouThePass” code base but with rewritten crypto; therefore treat it as an independent family until researchers converge on naming.
  • Cross-platform? – Windows only. No Linux or ESXi encryptor observed so far.
  • Notable side-effect: the malware clears SQL & Exchange transaction logs, so even if you have clean full backups you may lose one day of committed data.

TL;DR for Incident Handlers

“.dts” ransomware is human-operated, network-propagated and uses strong asymmetric encryption. No flaw, no free decryptor. Build, patch and MFA your external apps; keep cold backups. If hit, kill power, collect forensics, wipe, rebuild, restore from off-line backups – do NOT run public “decrypt” tools, they are scams. Stay safe and keep those backups off-site and off-line.