themida1005httpwwworeanscom

Hunt Hypothesis

This rule detects the presence of Themida-protected executables, a common anti-debugging and obfuscation technique frequently employed by malware authors to evade static analysis and dynamic inspection. Proactively hunting for these signatures in Azure Sentinel helps identify potentially compromised endpoints or malicious payloads that may be hiding in plain sight, allowing the SOC to investigate suspicious binaries before they execute their intended payload.

YARA Rule

rule themida1005httpwwworeanscom
{
      meta:
		author="malware-lu"
strings:
		$a0 = { B8 00 00 00 00 60 0B C0 74 58 E8 00 00 00 00 58 05 43 00 00 00 80 38 E9 75 03 61 EB 35 E8 00 00 00 00 58 25 00 F0 FF FF 33 FF 66 BB 19 5A 66 83 C3 34 66 39 18 75 12 0F B7 50 3C 03 D0 BB E9 44 }

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: A developer or sysadmin manually downloads and executes the Themida 10.05 packer utility (themida1005.exe or similar) from the vendor’s official website (http://www.oreans.com) to protect a custom internal application binary before deployment.

  • Filter/Exclusion: Exclude processes where the parent process is a known IDE (e.g., devenv.exe, code.exe, idea64.exe) or a terminal emulator (e.g., cmd.exe, powershell.exe, bash.exe) and the file path resides in a standard development directory (e.g., C:\Users\<User>\Projects\, C:\dev\, C:\work\).

• Scenario: A CI/CD pipeline agent (e.g., Jenkins, Azure DevOps, GitLab Runner) runs a build step that invokes the Themida packer as part of an automated release process, often triggered by a scheduled job or webhook.

  • Filter/Exclusion: Exclude executions where the parent process is a known CI/CD agent service (e.g., jenkins.exe, agent.exe, gitlab-runner.exe) or where the working directory contains typical CI/CD workspace markers (e.g., workspace/, builds/, artifacts/).

• Scenario: An IT support technician or system administrator uses a portable version of the Themida packer from a shared network drive or USB stick to re-protect a legacy application binary that was accidentally unpacked during troubleshooting.

  • Filter/Exclusion: Exclude executions where the executable path is located on a mapped network drive (e.g., \\fileserver\tools\, Z:\) or a removable drive (e.g., E:\, F:\) and the user account belongs to a privileged group (e