nPack111502006BetaNEOx

Hunt Hypothesis

This detection identifies potential early-stage malware activity or suspicious process execution patterns flagged by the specific nPack111502006BetaNEOx YARA signature within the Azure Sentinel environment. Proactive hunting for this low-severity indicator is essential to uncover stealthy adversary behaviors that may evade standard alerting thresholds, allowing the SOC team to validate and investigate emerging threats before they escalate into significant incidents.

YARA Rule

rule nPack111502006BetaNEOx
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 83 3D [5] 75 05 E9 01 00 00 00 C3 E8 41 00 00 00 B8 [4] 2B 05 [4] A3 [4] E8 5E 00 00 00 E8 E0 01 00 00 E8 EC 06 00 00 E8 F7 05 00 00 A1 [4] C7 05 [8] 01 05 [4] FF 35 [4] C3 C3 56 57 68 [4] FF 15 [4] 8B 35 [4] 8B F8 68 [4] 57 FF D6 68 [4] 57 A3 [4] FF D6 5F A3 [4] 5E 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

Here are 4 specific false positive scenarios for the nPack111502006BetaNEOx detection rule, including targeted filters and exclusions:

• Scenario: Scheduled Antivirus Definition Updates via WSUS

  • Context: The Windows Update Service (WUAUENG) or third-party AV agents (e.g., CrowdStrike Falcon, Microsoft Defender for Endpoint) periodically download and unpack signature definition updates. These processes often involve temporary extraction of compressed archives containing executable payloads that match the rule’s heuristic patterns.
  • Filter/Exclusion: Create a process exclusion for wuauclt.exe and MpCmdG.exe (Microsoft Defender) running under the SYSTEM or NT SERVICE\wuauserv user context, specifically when the parent process is svchost.exe.

• Scenario: Automated Software Deployment via SCCM/Intune

  • Context: During business hours, System Center Configuration Manager (SCCM) or Microsoft Intune pushes application patches to endpoints. The deployment agent (ccmexec.exe or CcmService) extracts installation packages (.msi/.cab) which triggers the YARA rule due to the presence of embedded scripts and compressed binaries similar to the detection logic.
  • Filter/Exclusion: Exclude file paths containing \Program Files\Microsoft Configuration Manager\ and process names ccmexec.exe, provided the user context is NT AUTHORITY\SYSTEM.

• Scenario: Backup Agent Incremental Scans

  • Context: Enterprise backup solutions like Veeam Agent or Rubrik perform incremental scans that involve reading and temporarily unpacking metadata files. The rule may flag these background operations as suspicious activity due to the high volume of file I/O and temporary artifact creation in the C:\ProgramData directory.
  • **Filter/Exclusion