PESHiELD02

Hunt Hypothesis

This detection identifies potential low-severity threats by leveraging the PESHiELD02 YARA signature to scan for specific file patterns indicative of emerging adversary activity. Proactive hunting in Azure Sentinel is essential to validate these signals early, ensuring that subtle indicators are not overlooked before they escalate into more severe incidents within the cloud environment.

YARA Rule

rule PESHiELD02
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 60 E8 00 00 00 00 41 4E 41 4B 49 4E 5D 83 ED 06 EB 02 EA 04 }

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 PESHiELD02 detection rule, including suggested filters and exclusions tailored for an enterprise environment:

• Scenario: Automated Patch Deployment via SCCM/Intune

  • Context: The System Center Configuration Manager (SCCM) or Microsoft Intune client executes a scheduled task to download and install security patches. During this process, the deployment agent (ccmsetup.exe or Microsoft.IntuneManagementAgent) spawns child processes that match the YARA signature’s behavior pattern for suspicious script execution or binary loading.
  • Filter/Exclusion: Create an exclusion based on the parent process name and path. Exclude alerts where the parent process is ccmexec.exe (SCCM) or Microsoft.IntuneManagementAgent.exe located in C:\Program Files\Microsoft Intune Management Agent\ or C:\Windows\CCM\.

• Scenario: Endpoint Protection Scanning by CrowdStrike Falcon

  • Context: The CrowdStrike Falcon sensor performs a real-time scan or an on-demand full system scan. The scanning engine (csfalcon.exe) frequently loads dynamic libraries and executes internal scripts that mimic the specific memory patterns or file hashes targeted by PESHiELD02, triggering alerts during high-I/O periods.
  • Filter/Exclusion: Implement a rule exclusion for processes running under the C:\Program Files\CrowdStrike\Falcon\ directory. Additionally, filter out events where the process command line contains keywords like “Scan,” “Update,” or “OnAccess.”

• Scenario: Scheduled Backup Jobs using Veeam Agent

  • Context: The nightly Veeam Agent for Windows runs a scheduled backup job. During the incremental scan phase, VeeamAgentService.exe spawns multiple worker threads that instantiate temporary executables to compress and encrypt data blocks