NsPacKV33LiuXingPing

Hunt Hypothesis

This YARA rule targets the NsPacKV33LiuXingPing signature, which is indicative of a specific malware variant or suspicious payload often associated with low-severity threats or early-stage reconnaissance. Proactively hunting for this signature in Azure Sentinel allows the SOC team to identify dormant or stealthy infections that may evade standard behavioral detections, ensuring timely containment before the adversary establishes persistence or exfiltrates data.

YARA Rule

rule NsPacKV33LiuXingPing
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 9C 60 E8 00 00 00 00 5D 83 ED 07 8D 85 [4] 80 38 00 74 }

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

• Scenario: A legacy Java-based enterprise application (e.g., an internal ERP or CRM module) is deployed via a .jar file that has been repackaged or obfuscated by a build tool like Maven or Gradle. The YARA rule may match specific byte patterns in the manifest or class files that resemble the NsPacKV33LiuXingPing signature, particularly if the application uses custom encryption or compression libraries.

  • Filter/Exclusion: Exclude files located in standard Java application directories (e.g., C:\Program Files\*\.jar, C:\opt\app\lib\*.jar) or exclude processes named java.exe or jre.exe when the file extension is .jar or .class.

• Scenario: An IT administrator uses WinRAR or 7-Zip to create a compressed archive of configuration files or logs for backup purposes. If the archive contains specific binary structures or headers that match the byte sequence targeted by the YARA rule, the archive file itself (.zip, .rar, .7z) may trigger the detection, especially if the compression algorithm produces similar entropy patterns.

  • Filter/Exclusion: Exclude files with extensions .zip, .rar, .7z, .tar, or .gz when the parent process is a known archiving tool (WinRAR.exe, 7z.exe, tar.exe) and the file size is below a certain threshold (e.g., < 100MB) to avoid flagging large legitimate backups.

• Scenario: A developer or DevOps engineer runs a Python script using PyInstaller to bundle an internal utility into a standalone executable. The resulting .exe file contains embedded Python bytecode and shared libraries that may exhibit byte patterns matching the `NsPacKV33LiuXingPing