nPackV111502006BetaNEOxuinC

Hunt Hypothesis

This detection identifies potential malicious activity associated with the specific YARA signature nPackV111502006BetaNEOxuinC, which may indicate the presence of a known or emerging threat actor leveraging this pattern within the environment. Proactive hunting for this indicator in Azure Sentinel is essential to validate its behavior and prevent potential low-severity incidents from evolving into larger security risks before they impact critical assets.

YARA Rule

rule nPackV111502006BetaNEOxuinC
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 83 3D 40 [3] 00 75 05 E9 01 00 00 00 C3 E8 41 00 00 00 B8 80 [3] 2B 05 08 [3] A3 3C [3] E8 5E 00 00 00 E8 E0 01 00 00 E8 EC 06 00 00 E8 F7 05 00 00 A1 3C [3] C7 05 40 [3] 01 00 00 00 01 05 00 [3] FF 35 00 [3] C3 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 nPackV111502006BetaNEOxuinC detection rule, including suggested filters and exclusions:

• Scenario: Scheduled Endpoint Protection Updates via Microsoft Defender for Endpoint

  • Context: The YARA signature likely matches a specific hash or string pattern found in the nPack update component used by Microsoft Defender. During nightly maintenance windows (e.g., 02:00 AM), the MsMpEng.exe process triggers an automated download and installation of definition updates, which mimics the behavior of the rule’s target signature.
  • Suggested Filter/Exclusion: Create a whitelist exclusion for the process path C:\Program Files\Microsoft Defender\MsMpEng.exe. Additionally, add a time-based filter to suppress alerts generated between 01:30 and 04:30 UTC on weekdays when this specific update job runs.

• Scenario: Deployment of Internal Patching Scripts via SCCM/Intune

  • Context: Enterprise IT teams often use System Center Configuration Manager (SCCM) or Microsoft Intune to push custom patches. The deployment agent (ccmexec.exe or intunagent) may extract a temporary package containing the nPackV111502006BetaNEOxuinC artifact during the installation phase, triggering the rule before the file is fully integrated into the system registry.
  • Suggested Filter/Exclusion: Exclude alerts where the parent process is identified as ccmexec.exe or intunagent.exe. Furthermore, filter out events occurring on specific “Patch Tuesday” windows (first Tuesday of every month) between 08:00 and 12:00 local time.

• **Scenario: Automated Backup Operations by Veeam or Comm