nPack113002006BetaNEOx

Hunt Hypothesis

This detection identifies potential execution of a specific beta-stage executable or script defined by the nPack113002006BetaNEOx YARA signature, which may indicate early-stage adversary activity involving new or modified software artifacts. Proactive hunting for this signal in Azure Sentinel is essential to validate legitimate beta deployments and rapidly distinguish them from novel threats that could evade standard signature-based defenses due to their low severity classification.

YARA Rule

rule nPack113002006BetaNEOx
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 83 3D [5] 75 05 E9 01 00 00 00 C3 E8 46 00 00 00 E8 73 00 00 00 B8 [4] 2B 05 [4] A3 [4] E8 9C 00 00 00 E8 2D 02 00 00 E8 DD 06 00 00 E8 2C 06 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 5 specific false positive scenarios for the nPack113002006BetaNEOx detection rule, including suggested filters and exclusions:

• Scenario: Legitimate deployment of Microsoft Defender Antivirus updates via Windows Update Agent.

  • Context: The YARA rule may flag the MpCmdRun.exe process when it downloads and installs new definition packs, as these often contain embedded scripts or compressed payloads that match the rule’s heuristic signatures for “suspicious script execution.”
  • Filter/Exclusion: Create a whitelist exclusion based on the file path: C:\Program Files\Windows Defender\MpCmdRun.exe and restrict the alert to only trigger if the parent process is NOT svchost.exe (specifically the wuauserv service).

• Scenario: Scheduled execution of enterprise-wide PowerShell scripts for inventory auditing.

  • Context: IT operations teams often run nightly PowerShell jobs (e.g., using PowerShell.exe) to query hardware or software inventories across endpoints. These scripts frequently utilize dynamic code generation or invoke external modules that mimic the behavior patterns detected by nPack113002006BetaNEOx.
  • Filter/Exclusion: Exclude alerts where the command line contains specific keywords such as InventoryAudit.ps1 or -ExecutionPolicy Bypass, and limit scope to known service accounts (e.g., DOMAIN\svc-inventory) running on scheduled task triggers rather than user interactive sessions.

• Scenario: Automated software distribution via Microsoft Endpoint Configuration Manager (MECM/SCCM).

  • Context: When SCCM pushes application updates or patches, the ccmexec.exe process often spawns child processes to extract and install packages. The extraction of compressed archives during this phase can trigger the YARA rule due to the presence of embedded