Armadillo50DllSiliconRealmsToolworks

Hunt Hypothesis

This rule detects the presence of the Armadillo50 DLL, a known tool associated with the Silicon Realms threat actor, indicating potential post-compromise activity or lateral movement within the environment. Proactively hunting for this artifact allows the SOC team to identify early-stage intrusions or dormant implants that may not yet trigger high-severity alerts, enabling faster containment of targeted threats.

YARA Rule

rule Armadillo50DllSiliconRealmsToolworks
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 83 7C 24 08 01 75 05 E8 DE 4B 00 00 FF 74 24 04 8B 4C 24 10 8B 54 24 0C E8 ED FE FF FF 59 C2 0C 00 6A 0C 68 [4] E8 E5 24 00 00 8B 4D 08 33 FF 3B CF 76 2E 6A E0 58 33 D2 F7 F1 3B 45 0C 1B C0 40 75 1F E8 8F 15 00 00 C7 00 0C 00 00 00 57 57 57 57 57 E8 20 15 00 00 83 C4 14 33 C0 E9 D5 00 00 00 0F AF 4D 0C 8B F1 89 75 08 3B F7 75 03 33 F6 46 33 DB 89 5D E4 83 FE E0 77 69 83 3D [4] 03 75 4B 83 C6 0F 83 E6 F0 89 75 0C 8B 45 08 3B 05 [4] 77 37 6A 04 E8 D7 23 00 00 59 89 7D FC FF 75 08 E8 EC 53 00 00 59 89 45 E4 C7 45 FC FE FF FF FF E8 5F 00 00 00 8B 5D E4 3B DF 74 11 FF 75 08 57 53 E8 2B C5 FF FF 83 C4 0C 3B DF 75 61 56 6A 08 FF 35 [4] FF 15 [4] 8B D8 3B DF 75 4C 39 3D [4] 74 33 56 E8 19 ED FF FF 59 85 C0 0F 85 72 FF FF FF 8B 45 10 3B C7 0F 84 50 FF FF FF C7 00 0C 00 00 00 E9 45 FF FF FF 33 FF 8B 75 0C 6A 04 E8 7D 22 00 00 59 C3 }

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 DevOps engineer uses the silicon-realms build tool (or a similar custom internal tool named toolworks) to compile or package a shared library (.dll) during a CI/CD pipeline execution on a build server. The process toolworks.exe loads armando50.dll (a helper library for memory mapping or symbol resolution) to perform the compilation.

  • Filter/Exclusion: Exclude processes where the parent process is a known CI/CD agent (e.g., jenkins.exe, azure-pipelines-agent.exe, github-runner.exe) or where the working directory matches the build artifact path (e.g., C:\builds\project-x\dist\).

• Scenario: An IT administrator performs a manual software deployment or patching task using a custom wrapper script that invokes toolworks.exe to extract or register a specific .dll component (armando50.dll) into a client machine’s system32 or application directory. This is a legitimate administrative action, not malicious code injection.

  • Filter/Exclusion: Exclude events where the user account belongs to a privileged group (e.g., Domain Admins, IT_Ops) and the process path is located in a trusted administrative tools directory (e.g., C:\AdminTools\, C:\Patching\).

• Scenario: A scheduled maintenance job (e.g., a Windows Task Scheduler task named Nightly_Data_Sync) runs a custom utility toolworks.exe that depends on armando50.dll for data serialization. The YARA rule triggers because the DLL is loaded by the executable, but this is a standard dependency load, not an unusual or suspicious behavior.

  • Filter/Exclusion: Exclude processes where the parent process is svchost.exe (indicating a service