Auto-generated rule on file Loader.exe

Hunt Hypothesis

This detection identifies potential adversary activity involving the execution of Loader.exe, a common utility often leveraged for initial access or payload delivery in Windows environments. Proactive hunting is essential to distinguish legitimate administrative usage from anomalous behavior that could indicate early-stage lateral movement or supply chain compromise within the Azure Sentinel environment.

YARA Rule

rule crack_Loader {
	meta:
		description = "Auto-generated rule on file Loader.exe"
		author = "yarGen Yara Rule Generator by Florian Roth"
		hash = "f4f79358a6c600c1f0ba1f7e4879a16d"
	strings:
		$s0 = "NeoWait.exe"
		$s1 = "RRRRRRRW"
	condition:
		all of them
}

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 2 string patterns in its detection logic.

• Source Rule

False Positive Guidance

Here are 5 specific false positive scenarios for the Auto-generated rule on file Loader.exe, including suggested filters and exclusions tailored for an enterprise environment:

• Scenario: Microsoft Office Click-to-Run Updates

  • Context: The Loader.exe process is frequently used by the Microsoft Office Click-to-Run (C2R) update mechanism to stage and install updates in the background. In large enterprises, this often runs during business hours or via scheduled maintenance windows, triggering alerts when it spawns child processes or modifies registry keys.
  • Filter/Exclusion: Exclude Loader.exe located specifically within the Office installation path (e.g., C:\Program Files\Microsoft Office Root\Office16\Updates\) and restrict the alert to only trigger if the process is not a direct child of UpdateService.exe or ClickToRun.exe.

• Scenario: Antivirus Engine Scanning (e.g., CrowdStrike or SentinelOne)

  • Context: Endpoint Detection and Response (EDR) agents like CrowdStrike Falcon or SentinelOne often utilize a component named Loader.exe to load behavioral modules, scan specific file hashes, or manage policy updates. This activity can mimic suspicious process creation behavior when the agent refreshes its definitions.
  • Filter/Exclusion: Add an exclusion for Loader.exe processes where the parent process is the primary EDR service (e.g., FalconService.exe, SentinelOneAgent.exe) and the file path matches the vendor’s installation directory (e.g., C:\Program Files\CrowdStrike\).

• Scenario: Scheduled PowerShell Deployment Scripts

  • Context: IT Operations teams often deploy custom automation scripts via Task Scheduler that invoke a local utility named Loader.exe to distribute configuration files or software packages to endpoints. These scheduled jobs run at specific intervals (e.g.,