ThemidaWinLicenseV10XV17XDLLOreansTechnologies

Hunt Hypothesis

This rule identifies the presence of Themida-protected executables, which adversaries frequently use to obfuscate malicious payloads and evade static analysis during initial access or privilege escalation. Proactively hunting for these signatures in Azure Sentinel allows the SOC to detect potentially hidden or packed binaries that may indicate stealthy persistence or command-and-control infrastructure within the environment.

YARA Rule

rule ThemidaWinLicenseV10XV17XDLLOreansTechnologies
{
      meta:
		author="malware-lu"
strings:
		$a0 = { B8 [4] 60 0B C0 74 58 E8 00 00 00 00 58 05 [4] 80 38 E9 75 03 61 EB 35 E8 00 00 00 00 58 25 00 F0 FF FF 33 FF 66 BB [2] 66 83 [2] 66 39 18 75 12 0F B7 50 3C 03 D0 BB [4] 83 C3 ?? 39 1A 74 07 2D 00 10 00 00 EB DA 8B F8 B8 [4] 03 C7 B9 [4] 03 CF EB 0A B8 [4] B9 [4] 50 51 E8 84 00 00 00 E8 00 00 00 00 58 2D [4] B9 [4] C6 00 E9 83 E9 ?? 89 48 01 61 E9 }

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 build engineer uses the Themida packer to protect a custom C++/C# DLL or executable before deploying it to production servers to prevent reverse engineering. The file is signed with the company’s internal code-signing certificate, but the YARA rule matches the specific version strings (v10x, v17x) and the Oreans Technologies copyright string embedded in the binary.

  • Filter/Exclusion: Exclude files where the code_signing_cert matches the internal enterprise certificate (e.g., *.corp.local) AND the file path resides in known development or build directories (e.g., C:\Builds\, D:\Src\).

• Scenario: An IT administrator installs or updates Oreans Technologies’ proprietary middleware (such as their .NET Remoting or licensing components) on application servers. The installer drops a DLL (e.g., Oreans.Licensing.dll or similar) that contains the Themida protection header, triggering the detection during the initial file creation or when the service starts and maps the DLL into memory.

  • Filter/Exclusion: Exclude processes or files where the parent_process is msiexec.exe or setup.exe AND the file_name matches *Oreans* or *Themida* in application-specific directories (e.g., C:\Program Files\CorpApp\).

• Scenario: A legacy application uses a Themida-protected installer stub (common in older commercial software or internal tools) that is executed via a scheduled task to perform nightly license validation or component updates. The stub is a small PE file that unpacks the main application, and its memory image or on-disk file matches the YARA signature for v10x or v17x. *