PEZipv10byBaGIE

Hunt Hypothesis

This detection identifies potential malicious activity involving PEZip archives that may be utilized by adversaries to obfuscate payloads or deliver compressed executables within the environment. Proactive hunting for this signature in Azure Sentinel is essential to uncover stealthy delivery mechanisms that could bypass standard static analysis and facilitate lateral movement through compressed data transfers.

YARA Rule

rule PEZipv10byBaGIE
{
      meta:
		author="malware-lu"
strings:
		$a0 = { D9 D0 F8 74 02 23 DB F5 F5 50 51 52 53 8D 44 24 10 50 55 56 57 D9 D0 22 C9 C1 F7 A0 55 66 C1 C8 B0 5D 81 E6 FF FF FF FF F8 77 07 52 76 03 72 01 90 5A C1 E0 60 90 BD 1F 01 00 00 87 E8 E2 07 E3 05 17 5D 47 E4 42 41 7F 06 50 66 83 EE 00 58 25 FF FF FF FF 51 }

condition:
		$a0
}

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 PEZipv10byBaGIE detection rule, along with recommended filters and exclusions:

• Scenario: Automated Backup Archiving by Veeam or Commvault

  • Context: Enterprise backup agents (e.g., Veeam.Backup.Service.exe or commvault.cmd) frequently generate temporary ZIP archives containing PE executables during nightly backup windows to optimize storage and transfer. The YARA rule may flag these compressed bundles as suspicious if they contain nested executable structures.
  • Filter/Exclusion: Exclude processes where the parent process name matches known backup agents (Veeam.Backup.Service.exe, commvault.cmd) AND the file path contains keywords like \Backup\ or \Archive\.

• Scenario: Software Deployment via Microsoft Endpoint Configuration Manager (SCCM)

  • Context: During application installation or patching cycles, SCCM (ccmsetup.exe) extracts and processes .msi or .cab packages that often manifest as PE-zipped containers. The rule may trigger when the deployment agent creates a temporary working directory containing these compressed executables.
  • Filter/Exclusion: Create an exclusion for file paths starting with C:\Windows\CCMCache\ and restrict detection to files created by the user context NT SERVICE\CcmExec.

• Scenario: Scheduled PowerShell Script Execution for Log Aggregation

  • Context: Security or IT operations teams often run scheduled PowerShell jobs (powershell.exe) that invoke compression libraries (like .NET’s System.IO.Compression.ZipFile) to bundle logs before sending them to SIEMs. These scripts may create temporary .zip files containing PE binaries representing the script’s own execution context.
  • Filter/Exclusion: Filter out events where the parent process is powershell.exe and the