PEQuake006forgat

Hunt Hypothesis

This detection identifies potential malicious or anomalous Portable Executable (PE) structures that deviate from standard formatting patterns, which may indicate obfuscated malware or fileless attack vectors. Proactively hunting for these anomalies in Azure Sentinel allows the SOC team to uncover stealthy threats that bypass traditional signature-based defenses before they escalate into active incidents.

YARA Rule

rule PEQuake006forgat
{
      meta:
		author="malware-lu"
strings:
		$a0 = { E8 A5 00 00 00 2D [2] 00 00 00 00 00 00 00 00 00 3D [2] 00 2D [2] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 4A [2] 00 5B [2] 00 6E [2] 00 00 00 00 00 6B 45 72 4E 65 4C 33 32 2E 64 4C 6C 00 00 00 47 65 74 50 72 6F 63 41 64 64 72 65 73 73 00 00 00 47 65 74 4D 6F 64 75 6C 65 48 61 6E 64 6C 65 41 00 00 00 4C 6F 61 64 4C 69 62 72 61 72 79 41 00 [2] 00 00 56 69 72 74 75 61 6C 41 6C 6C 6F 63 00 00 00 00 00 00 }

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 4 specific false positive scenarios for the PEQuake006forgat detection rule, including suggested filters and exclusions:

• Scenario: Automated Patch Deployment via WSUS/SCCM

  • Context: The System Center Configuration Manager (SCCM) or Windows Update for Business service executes a scheduled job to download and install cumulative updates. During this process, the wsusclient.exe or ccmexec.exe processes often generate new PE files in temporary directories that match the rule’s signature for “forgotten” or unverified binaries.
  • Suggested Filter/Exclusion: Exclude the specific parent process paths: C:\Windows\CCM\PolicyAgent\ccmexec.exe and C:\Windows\System32\usoc\DcpClient.dll. Additionally, add a filter to ignore alerts occurring within the defined maintenance window (e.g., 01:00–05:00) for these specific process names.

• Scenario: Microsoft Defender Antivirus Real-Time Scanning

  • Context: When MsMpEng.exe performs real-time scanning or cloud-delivered protection updates, it frequently extracts and stages PE files from the network into its quarantine or cache folders (C:\ProgramData\Microsoft\Windows Defender). These temporary artifacts often trigger the rule due to their transient nature and lack of established reputation history.
  • Suggested Filter/Exclusion: Create a path-based exclusion for C:\ProgramData\Microsoft\Windows Defender and C:\Program Files\Windows Defender. Configure the detection logic to suppress alerts where the file age is less than 5 minutes and the parent process is MsMpEng.exe.

• Scenario: Third-Party Backup Agent Execution (Veeam/Acronis)

  • Context: Enterprise backup agents like Veeam Backup & Rep