SPLayerv008

Hunt Hypothesis

This detection identifies potential lateral movement or file-based execution anomalies by leveraging the SPLayerv008 YARA signature to match specific malware characteristics within endpoint telemetry. Proactive hunting for this indicator in Azure Sentinel is essential to uncover early-stage threats that may evade standard alerting thresholds, allowing analysts to investigate low-severity signals before they evolve into significant incidents.

YARA Rule

rule SPLayerv008
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 8D 40 00 B9 [4] 6A ?? 58 C0 0C [2] 48 [2] 66 13 F0 91 3B D9 [8] 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 5 specific false positive scenarios for the SPLayerv008 detection rule, including suggested filters and exclusions tailored for an enterprise environment:

• Scenario: Scheduled Antivirus Engine Updates

  • Context: The YARA rule triggers when the Microsoft Defender or CrowdStrike agent performs a scheduled definition update. These updates often involve unpacking compressed archives (.cab or .zip) containing new signatures, which mimics the behavior of a lateral movement or payload extraction attack.
  • Filter/Exclusion: Create an exclusion based on the process name MsMpEng.exe (Microsoft Defender) and CrdSvc.exe (CrowdStrike). Additionally, exclude file paths located within the standard update directories: C:\ProgramData\Microsoft\Windows Defender\Platform\* or C:\Program Files\CrowdStrike\*\*.cab.

• Scenario: Enterprise Backup Agent Operations

  • Context: During nightly backup windows, agents like Veeam or Commvault extract large datasets from compressed storage to temporary staging areas before archiving. The YARA signature detects the extraction of executable-like artifacts within these temporary folders as suspicious activity.
  • Filter/Exclusion: Exclude processes named VeeamTransport.exe and vssvc.exe. Apply a path-based exclusion for the backup staging directories, such as D:\BackupStaging\* or C:\ProgramData\Veeam\Backup\*.tmp, ensuring the rule ignores file creation events within these specific paths.

• Scenario: Software Deployment via SCCM/Intune

  • Context: When System Center Configuration Manager (SCCM) or Microsoft Intune pushes a new application package to endpoints, it extracts installation binaries from .msi or .appx packages. The rule flags the extraction of these installer components as potential malicious payload