MSLRHv032aemadicius

Hunt Hypothesis

This detection identifies potential malicious activity by matching file artifacts against the specific signature defined in the MSLRHv032aemadicius YARA rule. The SOC team should proactively hunt for this indicator within Azure Sentinel to uncover early-stage threats that may not yet trigger high-severity alerts, ensuring comprehensive coverage of low-fidelity but significant adversary behaviors.

YARA Rule

rule MSLRHv032aemadicius
{
      meta:
		author="malware-lu"
strings:
		$a0 = { E8 EB 0C 00 00 E8 F6 FF FF FF E8 F2 FF FF FF 83 C4 08 74 04 75 02 EB 02 EB 01 81 74 04 75 02 EB 02 EB 01 81 0F 31 50 0F 31 E8 0A 00 00 00 E8 EB 0C 00 00 E8 F6 FF FF FF E8 F2 FF FF FF 83 C4 08 2B 04 24 74 04 75 02 EB 02 EB 01 81 83 C4 04 E8 0A 00 00 00 E8 }
	$a1 = { EB 05 E8 EB 04 40 00 EB FA E8 0A 00 00 00 E8 EB 0C 00 00 E8 F6 FF FF FF E8 F2 FF FF FF 83 C4 08 74 04 75 02 EB 02 EB 01 81 E8 0A 00 00 00 E8 EB 0C 00 00 E8 F6 FF FF FF E8 F2 FF FF FF 83 C4 08 74 04 75 02 EB 02 EB 01 81 50 E8 02 00 00 00 29 5A 58 6B C0 03 }
	$a2 = { E8 EB 0C 00 00 E8 F6 FF FF FF E8 F2 FF FF FF 83 C4 08 74 04 75 02 EB 02 EB 01 81 74 04 75 02 EB 02 EB 01 81 0F 31 50 0F 31 E8 0A 00 00 00 E8 EB 0C 00 00 E8 F6 FF FF FF E8 F2 FF FF FF 83 C4 08 2B 04 24 74 04 75 02 EB 02 EB 01 81 83 C4 04 E8 0A 00 00 00 E8 EB 0C 00 00 E8 F6 FF FF FF E8 F2 FF FF FF 83 C4 08 3D FF FF FF 00 EB 01 68 EB 02 CD 20 EB 01 E8 76 1B EB 01 68 EB 02 CD 20 EB 01 E8 CC 66 B8 FE 00 74 04 75 02 EB 02 EB 01 81 66 E7 64 74 04 75 02 EB 02 EB 01 81 E8 0A 00 00 00 E8 EB 0C }

condition:
		$a0 or $a1 or $a2 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 3 string patterns in its detection logic.

• Source Rule

False Positive Guidance

Here are 5 specific false positive scenarios for the MSLRHv032aemadicius detection rule, along with suggested filters and exclusions:

• Scenario: Microsoft Defender Antivirus Scheduled Scans

  • Context: The YARA signature often triggers on the MsMpEng.exe process when it performs a scheduled full scan or updates its virus definition database. During these operations, the engine loads various heuristic modules that match the “emadicius” pattern within temporary memory regions.
  • Filter/Exclusion: Exclude processes where the command line contains --scheduled-scan and the parent process is MsMpEng.exe. Alternatively, create a rule exclusion for the file path C:\Program Files\Windows Defender\MsMpEng.exe during standard business hours (08:00–18:00).

• Scenario: SCCM/MECM Software Deployment Tasks

  • Context: When System Center Configuration Manager (SCCM) deploys new applications or patches, the ccmsetup.exe and associated installation agents often spawn child processes that unpack compressed payloads. These temporary extraction activities can mimic the binary structure detected by the MSLRHv032aemadicius rule.
  • Filter/Exclusion: Filter alerts where the parent process is ccmexec.exe or ccmsetup.exe. Add an exclusion for file paths under C:\Windows\CCM\ and C:\ProgramData\Microsoft\MSCCM\.

• Scenario: Active Directory Group Policy Updates

  • Context: During the standard Group Policy refresh cycle (typically every 90 minutes), the gpupdate.exe process interacts with the registry and file system to apply new policies. The rule may flag the policy engine’s interaction with specific XML configuration files as a potential anomaly matching