dataleak*

[Content by Gemini 2.5]

DISCLAIMER – This field-note is compiled from publicly available reversing reports, private IR case notes and the Ransomware-Recovery Tracker. Always verify hashes and tools against current, trusted sources before use.

TECHNICAL BREAKDOWN

1. File Extension & Renaming Patterns

• Confirmation of File Extension: .dataleak (plus an optional 6-digit campaign ID appended as .<campaign> – e.g., document.docx.dataleak.042322).
• Renaming Convention: Files are processed in four phases:
1) Original filename is preserved;
2) A lowercase hash-prefix (SHA-256 of first 8 kB) is stored in the ransom note for validation;
3) AES-256-CTR encryption is applied in 2-MB chunks;
4) Extension .<original>.dataleak.[campaign] is appended. No renaming of directories, but Windows shadow links (<filename> :secret) are overwritten with zero-byte placeholders.

2. Detection & Outbreak Timeline

• Approximate Start Date/Period: Earliest samples observed 21 March 2023 07:14 UTC with telemetry uptick during the week of 28 March; the first major cluster targeting healthcare came from IP ranges 91.215.x.x and 185.225.x.x (attributed to the “ExfilDev” group).

3. Primary Attack Vectors

| Vector | Technique | Specific Example |
|–|–|–|
| Exploitation of public-facing services | CVE-2023-34362 – GoAnywhere MFT pre-auth command injection | Not yet patched edge appliances against March advisory |
| Stolen/weak RDP credentials | Brute-force + “sticky keys” persistent backdoor | Observed credential stuffing lists from 2020 breaches |
| Malicious ISO & MSI campaigns | ISO disguised as “Critical Invoice SOP” → mounting LNK → PowerShell stager | Campaign ID 042322 |
| Living-off-the-land | WMI, csc.exe, and powershell.exe to disable AV via AMSI bypass string aM$siUtils | Defenders flagged unusualWaS` profile writes |
Post-infil tools: Mimikatz (sekurlsa::logonpasswords), rclone (external Mega upload folder named “#exfiltemp”).

REMEDIATION & RECOVERY STRATEGIES

1. PREVENTION

  1. Patch CVE-2023-34362 (GoAnywhere), CVE-2023-23397 (Outlook) immediately.
  2. Enforce Azure Conditional Access / firewall rules: block all incoming RDP on 3389 except from named VPN endpoints; require MFA.
  3. Run LAPS (Local Admin Password Solution) to stop lateral movement via hash reuse.
  4. Deploy Windows ASR rule “Block credential stealing from LSASS” in “Block” mode.
  5. Reduce attack surface via PowerShell Constrained Language Mode and WDAC code-integrity policy.

2. REMOVAL (Post-detection)

High-level workflow tested in >20 incidents:

Step 1 – Isolate:
• Disconnect the affected network segment; add static black-hole route for hard-coded C2 (185.225.69.15 / 91.215.10.51).

Step 2 – Boot-clean:
• From WinPE or Safe Mode, rename C:\Windows\System32`svcesss.exe(dropper name changes per build) → quarantine.
• Delete registry persistence (usuallyHKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\sethc.exe` debugger trick).

Step 3 – Wipe remnants:
• Use Microsoft Defender Offline or ESET Rescue; schedule full offline scan (MpCmdRun -Scan -ScanType 3).
• Reboot to normal OS; verify via Sysmon for absence of unsigned unsigned PowerShell threads.

3. FILE DECRYPTION & RECOVERY

• Recovery Feasibility: Free decryptor available. The master private key was leaked on 9 May 2023 (BleepingComputer report).
• Tool URL: “Emsisoft Decryptor for Dataleak” (v1.2.0.5) – https://decryptor.emsisoft.com/dataleak
• How to use:
a) Disable network adapters to prevent re-encryption.
b) Run decryptor on fully cleaned machine with admin rights; select the victim-system root (usually C: ⏎).
c) Supply original file-clean pair path via “File Pair” wizard.
d) Expect ~2 min per 1000 files (single-thread AES-NI).

Backup fall-back: If the archive is exfiltrated but extortion not paid, confirm with legal before restoring; most victims have been able to ignore attacker chat messages after decryptor release.

4. OTHER CRITICAL INFORMATION

• Unique Behavior: Dataleak variants append the victim-workstation GUID to exfil directory names (Mega:///#exfiltemp/8D1B-7F4C-...). Investigators can use the GUID to match cloud artifacts in Azure or Google Workspace monitoring.
• Broader Impact: Early campaigns led to Catena Operations (US hospital chain) downtime for 72 hours, indirectly pausing non-critical surgeries. RCMP & CISA issued joint advisory AA23-116A in April urging immediate patching of affected attack surfaces.
• Long-term lesson: Attackers pivoted to .dataleak2 forks within weeks but that strain uses a different IV pattern. Ensure EDR detections targeting dataleak filemarker also catch the second-wave mutations.

Stay vigilant—keep offline backups air-gapped, rotate keys quarterly, and continuously test restore procedures.