JDPack2xJDPack

Hunt Hypothesis

This hunt detects the presence of the JDPack2xJDPack malware signature identified by a specific YARA rule, which often indicates early-stage reconnaissance or lateral movement activities within the environment. Proactively hunting for this indicator in Azure Sentinel is essential to identify low-severity anomalies that may serve as precursors to more significant compromise events before they escalate into critical incidents.

YARA Rule

rule JDPack2xJDPack
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 68 51 40 00 68 04 25 40 00 64 A1 00 00 00 00 }

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 JDPack2xJDPack detection rule, including suggested filters and exclusions:

• Scenario: Scheduled Deployment of Java Runtime Updates via SCCM/Intune

  • Context: Enterprise endpoints often run scheduled tasks (e.g., Task Scheduler or SCCM Client) that deploy the latest JRE/JDK updates using the official installer (jre-8u391-windows-x64.exe). The installation process extracts and executes the JDPack2xJDPack component to handle configuration files, triggering the YARA rule.
  • Filter/Exclusion: Exclude processes where the parent executable is ccmsetup.exe (SCCM) or Microsoft.IntuneManagementExtension.exe, specifically when the file path contains \Windows\CCM\ and the user context is SYSTEM.

• Scenario: Automated Patching by Endpoint Protection Suites

  • Context: Security suites like CrowdStrike Falcon, Carbon Black, or Symantec Endpoint Protection frequently scan Java applications in real-time. During a background update of their own Java-based modules, the scanner may spawn a temporary process that matches the JDPack2xJDPack signature while unpacking its internal libraries.
  • Filter/Exclusion: Create an exclusion for processes with ImageName matching FalconSensor.exe, cbengine.exe, or Symantec Endpoint Protection Client.exe. Additionally, filter out events where the process start time aligns with known maintenance windows (e.g., 02:00–04:00 local time).

• Scenario: Execution of Internal Enterprise Java Applications

  • Context: Custom internal tools built on the Java stack (e.g., a proprietary HR portal launcher or inventory management tool named `CorpHR_Launcher