Themida18xxOreansTechnologies

Hunt Hypothesis

This hypothesis targets the presence of Themida 18xx packers, a commercial software protection tool frequently abused by threat actors to obfuscate malicious binaries and evade static analysis. Proactively hunting for these signatures in Azure Sentinel allows the SOC to identify potentially compromised workloads or deployed backdoors that may be hidden within legitimate applications, reducing the time to detect stealthy persistence mechanisms.

YARA Rule

rule Themida18xxOreansTechnologies
{
      meta:
		author="malware-lu"
strings:
		$a0 = { B8 [4] 60 0B C0 74 68 E8 00 00 00 00 58 05 53 00 00 00 80 38 E9 75 13 61 EB 45 DB 2D 37 [3] FF FF FF FF FF FF FF FF 3D 40 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 00 00 83 C3 67 }
	$a1 = { B8 [4] 60 0B C0 74 68 E8 00 00 00 00 58 05 53 00 00 00 80 38 E9 75 13 61 EB 45 DB 2D 37 [3] FF FF FF FF FF FF FF FF 3D 40 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 00 00 83 C3 67 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 26 00 00 00 B9 EF 01 00 00 C6 00 E9 83 E9 05 89 48 01 61 E9 }

condition:
		$a0 at pe.entry_point or $a1 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 2 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: A developer or DevOps engineer is running a local build pipeline or CI/CD agent (e.g., Jenkins, GitLab Runner, or Azure DevOps) that compiles or packages a C++/C# application protected by Themida 18.x for release. The YARA rule may match the in-memory state of the compiler or linker process, or the resulting executable file during the staging phase before it is moved to the final artifact repository.

  • Filter/Exclusion: Exclude processes where the parent process is a known build tool (e.g., msbuild.exe, dotnet.exe, java.exe for Maven/Gradle) or where the file path resides within standard build directories (e.g., C:\builds\, D:\artifacts\, .\bin\Debug\).

• Scenario: An IT administrator is performing a scheduled software inventory or asset discovery scan using tools like SCCM (System Center Configuration Manager), PDQ Inventory, or Lansweeper. These tools often read executable headers or perform lightweight integrity checks on installed applications, which may trigger a YARA match against the Themida-protected binaries on the endpoint.

  • Filter/Exclusion: Exclude events where the initiating process is a known inventory agent (e.g., ccmexec.exe, pdqagent.exe, lansweeper.exe) or where the operation is a “read” or “scan” action rather than an execution or write action.

• Scenario: A security team is conducting a periodic vulnerability assessment or malware scan using enterprise AV/EDR solutions (e.g., CrowdStrike Falcon, SentinelOne, or Microsoft Defender for Endpoint) that perform deep file scanning. The scanner loads the Themida-protected executable into memory to analyze its structure, potentially triggering the YARA rule if the rule is designed to match in-memory signatures or specific header patterns.