CipherWallSelfExtratorDecryptorGUIv15

Hunt Hypothesis

This rule detects the execution of the CipherWall self-extractor and decryptor GUI, a component often used by ransomware groups to unpack payloads or decrypt files during an attack. Proactively hunting for this artifact allows the SOC to identify early-stage ransomware activity or post-exploitation tooling before encryption or lateral movement occurs.

YARA Rule

rule CipherWallSelfExtratorDecryptorGUIv15
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 90 61 BE 00 10 42 00 8D BE 00 00 FE FF C7 87 C0 20 02 00 F9 89 C7 6A 57 83 CD FF EB 0E 90 90 90 90 8A 06 46 88 07 47 01 DB 75 07 8B 1E 83 EE FC 11 DB 72 ED B8 01 00 00 00 01 DB 75 07 8B 1E 83 EE FC 11 DB 11 C0 01 DB 73 EF 75 09 8B 1E 83 EE FC 11 DB 73 E4 }

condition:
		$a0 at pe.entry_point
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

• Microsoft Defender for Endpoint — Custom indicators / advanced hunting
• Email Gateway — Attachment scanning
• File Share Monitoring — Periodic scanning of shared drives
• YARA CLI — Manual threat hunting on endpoints

This rule contains 1 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: An administrator manually runs the CipherWallSelfExtratorDecryptorGUIv15.exe utility from the vendor’s installation directory or a shared network drive to decrypt a specific file for a user who lost access to their encrypted container.
  • Filter/Exclusion: Exclude processes where the parent process is explorer.exe or cmd.exe and the image path contains the known vendor install directory (e.g., C:\Program Files\CipherWall\ or \\fileserver\cipherwall_tools\).
• Scenario: A scheduled task or PowerShell script in a deployment pipeline automatically invokes the decryptor GUI to process a batch of files after a nightly backup or migration job completes.
  • Filter/Exclusion: Exclude executions where the parent process is Taskengw.exe (Windows Task Scheduler) or powershell.exe, and the command line arguments include specific batch-processing flags or reference a known job ID.
• Scenario: A security engineer or IT support agent uses the GUI tool interactively to verify decryption integrity during a routine audit or incident response, launching it from a temporary directory or a USB drive.
  • Filter/Exclusion: Exclude processes where the user account belongs to a specific security or IT support group (e.g., SecurityTeam, ITSupport) and the process is launched from a non-standard path like C:\Temp\ or a removable drive letter (e.g., E:\).
• Scenario: A third-party application or service that integrates with CipherWall’s SDK spawns the decryptor GUI as a child process to handle file-level decryption requests programmatically.
  • Filter/Exclusion: Exclude executions where the parent process is a known integration service executable (e.g., cipherwall_service.exe, vault_agent.exe, or a specific Java/.NET application) rather than a standard shell or