RLPack118aPlib043ap0x

Hunt Hypothesis

This hunt hypothesis detects potential malicious activity from a specific library or executable identified by the YARA signature RLPack118aPlib043ap0x, which may indicate early-stage reconnaissance or a known benign process requiring validation. A SOC team should proactively hunt for this indicator in Azure Sentinel to distinguish between legitimate application behavior and stealthy adversary presence, ensuring that low-severity signals do not mask emerging threats within the environment.

YARA Rule

rule RLPack118aPlib043ap0x
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 60 E8 00 00 00 00 8B 2C 24 83 C4 ?? 8D B5 1A 04 00 00 8D 9D C1 02 00 00 33 FF E8 61 01 00 00 EB 0F FF 74 37 04 FF 34 37 FF D3 83 C4 ?? 83 C7 ?? 83 3C 37 00 75 EB 83 BD 06 04 00 00 00 74 0E 83 BD 0A 04 00 00 00 74 05 E8 D7 01 00 00 8D 74 37 04 53 6A ?? 68 [4] 68 [4] 6A 00 FF 95 A7 03 00 00 89 85 16 04 00 00 5B FF B5 16 04 00 00 56 FF D3 83 C4 ?? 8B B5 16 04 00 00 8B C6 EB 01 }

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 5 specific false positive scenarios for the detection rule RLPack118aPlib043ap0x, including suggested filters and exclusions tailored for an enterprise environment:

• Scenario: Automated Patch Deployment via SCCM

  • Context: The Microsoft Endpoint Configuration Manager (SCCM) or Intune agent executes a scheduled task to deploy .NET framework updates or application patches. During this process, the deployment engine extracts compressed packages and loads specific DLLs that match the signature pattern of RLPack118aPlib043ap0x.
  • Suggested Filter: Create an exclusion based on the parent process name (ccmsetup.exe or Microsoft.Windows.IntuneManagementAgent) and restrict the rule to trigger only when the file hash does not match known good hashes from the patch repository.

• Scenario: Antivirus Engine Scanning (CrowdStrike/Defender)

  • Context: The real-time protection engine of CrowdStrike Falcon or Microsoft Defender for Endpoint performs a deep scan on user directories. When scanning large archives containing embedded libraries, the AV engine’s internal unpacking utility generates artifacts that mimic the detection logic of this rule.
  • Suggested Filter: Exclude processes running under the C:\Program Files\CrowdStrike\ or C:\ProgramData\Microsoft\Windows Defender\ directories from triggering this specific YARA rule, as these are trusted security components.

• Scenario: CI/CD Pipeline Build Artifacts

  • Context: In a DevOps environment using Jenkins or Azure DevOps, the build agent compiles source code and packages it into deployment artifacts. The packaging tool (e.g., MSBuild or NuGet) utilizes a library component that matches the RLPack118aPlib043ap0x signature during the “Package” phase of the