MSLRHv032afakeASPack212emadicius

Hunt Hypothesis

This detection identifies potential adversary activity involving fake or malicious AS Pack components that mimic legitimate system behavior to evade initial scrutiny. A proactive hunt is essential in Azure Sentinel to uncover stealthy lateral movement or persistence mechanisms that may bypass standard signature-based defenses despite their low severity classification.

YARA Rule

rule MSLRHv032afakeASPack212emadicius
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 60 E8 03 00 00 00 E9 EB 04 5D 45 55 C3 E8 01 00 00 00 EB 5D BB ED FF FF FF 03 DD 81 EB 00 A0 02 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 50 E8 02 00 00 00 29 5A 58 6B C0 03 E8 02 00 00 00 29 5A 83 C4 04 58 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 }

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

Here are 4 specific false positive scenarios for the detection rule MSLRHv032afakeASPack212emadicius, along with recommended filters and exclusions tailored for a legitimate enterprise environment:

• Scenario: Automated Endpoint Protection Scans

  • Context: The YARA signature may match heuristic patterns found in the scanning engines of major EDR solutions. When tools like CrowdStrike Falcon, Microsoft Defender for Endpoint, or SentinelOne perform scheduled full-system scans, their background processes often load dynamic libraries that mimic the structural characteristics flagged by this rule.
  • Filter/Exclusion: Create an exclusion based on the executable path and process name. Exclude any detection where Process Name matches C:\Program Files\CrowdStrike\FalconSensor\csfalcon.exe, C:\Program Files\Microsoft Defender\MsMpEng.exe, or C:\Program Files\SentinelOne\SentinelOne\SentinelService.exe.

• Scenario: Patch Management and Software Deployment

  • Context: Enterprise deployment tools frequently install updates that include compressed archives or installer packages containing embedded manifests similar to the rule’s signature. During a scheduled maintenance window, tools like Microsoft Endpoint Configuration Manager (MECM/SCCM) or Ivanti Neurons may trigger this alert while extracting and installing the “ASPack212” component of a cumulative update.
  • Filter/Exclusion: Exclude alerts where the Parent Process is ccmexec.exe (System Center Configuration Manager) or installshield.exe, specifically when the event timestamp falls within the defined maintenance window (e.g., Sundays 02:00–04:00 UTC).

• Scenario: Backup and Archiving Operations

  • Context: Enterprise backup solutions often create temporary staging files that utilize compression