ExeSafeguardv10simonzh

Hunt Hypothesis

This detection identifies potential execution of suspicious executable files matching the ExeSafeguard signature, which may indicate early-stage adversary activity such as fileless attacks or unauthorized software deployment. Proactively hunting for this pattern in Azure Sentinel allows the SOC team to validate legitimate processes against known threats before they escalate into more severe incidents, ensuring robust endpoint protection within the cloud environment.

YARA Rule

rule ExeSafeguardv10simonzh
{
      meta:
		author="malware-lu"
strings:
		$a0 = { C0 5D EB 4E EB 47 DF 69 4E 58 DF 59 74 F3 EB 01 DF 75 EE 9A 59 9C 81 C1 E2 FF FF FF EB 01 DF 9D FF E1 E8 51 E8 EB FF FF FF DF 22 3F 9A C0 81 ED 19 18 40 00 EB 48 EB 47 DF 69 4E 58 DF 59 79 EE EB 01 DF 78 E9 DF 59 9C 81 C1 E5 FF FF FF 9D FF E1 EB 51 E8 EE }

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 3-5 specific false positive scenarios for the ExeSafeguardv10simonzh detection rule, including suggested filters and exclusions:

• Scenario: Microsoft Office Click-to-Run Update Service

  • Context: The OfficeClickToRun.exe process frequently launches temporary executable instances to apply feature updates or repair installations. These processes often match the YARA signature due to similar PE header structures used by Safeguard components.
  • Filter/Exclusion: Exclude any alert where the parent process is Microsoft Office Click-to-Run.exe (OfficeClickToRun.exe) and the file path contains \AppData\Local\Microsoft\Office\ClickToRun.

• Scenario: Scheduled Antivirus Definition Updates via SCCM

  • Context: System Center Configuration Manager (SCCM) triggers a nightly job to push definition updates. The deployment agent (ccmexec.exe) spawns ExeSafeguard child processes that mimic the rule’s detection logic during the installation phase of new signatures.
  • Filter/Exclusion: Create an exclusion for events occurring between 01:00 and 04:00 UTC where the parent process is ccmexec.exe and the command line contains arguments related to “SoftwareUpdate” or “DefinitionUpdate”.

• Scenario: Endpoint Protection Policy Enforcement by CrowdStrike

  • Context: When CrowdStrike Falcon agents enforce new security policies, they often spawn helper executables that interact with system files. The YARA rule may flag these policy enforcement binaries as suspicious because they share code signatures with the Safeguard module being monitored.
  • Filter/Exclusion: Filter out alerts where the process name is CnsNotify.exe or FalconService.exe and the file hash matches a known “Good” list of CrowdStrike components maintained in