Executive Summary

• Threat family: Warlock Ransomware (new or evolving strain observed in 2025).

• Category: Double-extortion ransomware. Encrypts files and threatens data leaks.

• Distribution: Phishing attachments, RDP brute-force, and exploitation of unpatched software.

• Impact: Full system encryption, exfiltration of business-critical data, lateral spread across enterprise networks.

• Action now: Network segmentation, backup validation, strict patch management, and endpoint monitoring.

Technical Overview

• Infection vector:

  • Malicious Office macros/PDFs.

  • RDP brute force attacks.

  • Exploitation of exposed services (VPN gateways, unpatched web servers).

• Encryption behavior:

  • AES/RSA hybrid scheme.

  • Appends .warlock extension.

  • Drops ransom note WARLOCK_README.txt.

• Command & Control:

  • HTTP(S) with domain-generated algorithm (DGA).

  • Some samples tunnel over TOR hidden services.

• Data theft:

  • File exfiltration to attacker-controlled cloud servers before encryption.

MITRE ATT&CK Mapping

• Initial Access: Phishing (T1566), Exploit Public-Facing Application (T1190).

• Execution: Command-Line Interface (T1059).

• Persistence: Registry Run Keys (T1547).

• Exfiltration: Exfiltration to Cloud Storage (T1567.002).

• Impact: Data Encrypted for Impact (T1486).

Indicators of Compromise (IoCs)

• File: warlock.exe, warlock_loader.dll

• Registry keys: HKCU\Software\Warlock

• Extensions: .warlock

• Domains (samples): darklock[.]onion, wlck-gate[.]xyz

Threat Hunting Queries

Splunk:

index=windows_logs EventCode=4688
| search process_name="*warlock*.exe" OR process_name="*warlock*.dll"

Sigma (Ransom note drop):

title: Warlock Ransom Note Creation
logsource: windows
detection:
  selection:
    TargetFilename|endswith: "WARLOCK_README.txt"
condition: selection
level: high

Recommended Countermeasures

1. Patch management: Close vulnerabilities used by Warlock.

2. Restrict RDP exposure: Enforce MFA, IP allowlists, and lockouts.

3. EDR policies: Block suspicious process creation (mass encryption).

4. Segmentation: Stop lateral spread.

5. Backups: Keep offline, test restore.

6. Incident response plan: Include ransomware containment & negotiation policies.

Business Impact

• Financial loss: Ransom demands ($500K–$5M range).

• Data breach risk: Double-extortion threatens leaks.

• Regulatory impact: GDPR/HIPAA fines if personal data is exposed.

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