marcher2

Hunt Hypothesis

The marcher2 YARA rule detects potential malicious activity associated with the Marcher malware family, which is known for its persistence and data exfiltration capabilities. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate early-stage compromises that may evade traditional detection methods.

YARA Rule

rule marcher2
{
	meta:
		author = "Antonio S. <[email protected]>"
		source = "https://analyst.koodous.com/rulesets/890"
	strings:
		$a = "HDNRQ2gOlm"
		$b = "lElvyohc9Y1X+nzVUEjW8W3SbUA"
	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

• Scenario: Scheduled System Maintenance Task
  Description: A legitimate system maintenance task (e.g., Task Scheduler job) runs a script that matches the YARA rule due to similar file names or strings.
  Filter/Exclusion: Exclude files with Task Scheduler in the process name or files with a .bat or .ps1 extension that are scheduled via schtasks.exe.

• Scenario: Antivirus Quarantine Scan
  Description: An antivirus tool (e.g., Kaspersky, Bitdefender) moves a file to quarantine, which may trigger the rule due to temporary file presence.
  Filter/Exclusion: Exclude files with a quarantine or tmp directory path, or files with a known antivirus quarantine signature.

• Scenario: Log File Parsing by SIEM Tool
  Description: A SIEM tool (e.g., Splunk, ELK Stack) parses log files and generates temporary files that match the YARA rule.
  Filter/Exclusion: Exclude files containing the string log or tmp in their filename, or files with a log directory path.

• Scenario: PowerShell Script for System Monitoring
  Description: A PowerShell script (e.g., PowerShell ISE, PowerShell Core) runs a script that includes strings matching the YARA rule for system monitoring.
  Filter/Exclusion: Exclude files with a .ps1 extension and a PowerShell process name, or files executed via powershell.exe with a known monitoring script name.

• Scenario: Database Backup Job
  Description: A database backup job (e.g., SQL Server Agent Job, MySQL Backup Script) generates temporary files that match the YARA rule.
  Filter/Exclusion: Exclude files with a backup or