Morphinev33SilentSoftwareSilentShieldc2005

Hunt Hypothesis

This hypothesis targets the presence of Silent Software Silent Shield, a known commercial security tool that can be leverized by adversaries to hide processes or files from detection, indicating potential stealth operations or supply chain compromises. Proactively hunting for this signature in Azure Sentinel allows the SOC to identify unauthorized or unexpected instances of this software, helping to distinguish legitimate administrative usage from malicious persistence or obfuscation techniques.

YARA Rule

rule Morphinev33SilentSoftwareSilentShieldc2005
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 28 [3] 00 00 00 00 00 00 00 00 40 [3] 34 [3] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 4C [3] 5C [3] 00 00 00 00 4C [3] 5C [3] 00 00 00 00 4B 65 52 6E 45 6C 33 32 2E 64 4C 6C 00 00 47 65 74 50 72 6F 63 }
	$a1 = { 28 [3] 00 00 00 00 00 00 00 00 40 [3] 34 [3] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 4C [3] 5C [3] 00 00 00 00 4C [3] 5C [3] 00 00 00 00 4B 65 52 6E 45 6C 33 32 2E 64 4C 6C 00 00 47 65 74 50 72 6F 63 41 64 64 72 65 73 73 00 00 4C 6F 61 64 4C 69 62 72 61 72 79 41 }

condition:
		$a0 or $a1
}

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

• Legitimate Deployment of Silent Software Installers: Enterprise IT teams frequently use silent installers (e.g., msiexec /i setup.msi /qn or custom .exe wrappers) for mass deployments of applications like Adobe Creative Cloud, Java, or internal tools via SCCM or PDQ Deploy. These installers often bundle components that match the “SilentShield” signature.

  • Filter/Exclusion: Exclude processes where the command line contains /qn, /silent, or /passive and the parent process is a known deployment tool (e.g., ccmexec.exe, pdqdeploy.exe, or taskeng.exe).

• Scheduled Maintenance Jobs for Third-Party Utilities: Many enterprise utilities (e.g., antivirus, disk defragmentation, or backup agents) run scheduled tasks that execute silent maintenance scripts. These scripts may invoke helper binaries that trigger the YARA rule.

  • Filter/Exclusion: Exclude executions where the parent process is svchost.exe (specifically for known service groups like GroupPolicy or Backup) or taskschd.exe, and the working directory is under C:\Program Files\ or C:\ProgramData\.

• Application Auto-Update Mechanisms: Software like Slack, Zoom, or internal Java-based apps often use silent update mechanisms that download and execute new versions in the background. These update binaries may be signed and located in user-specific or application-specific directories.

  • Filter/Exclusion: Exclude processes where the executable path resides in C:\Users\<username>\AppData\Local\ or C:\Program Files\<AppName>\Update\ and the process name matches known updater patterns (e.g., update.exe, auto-updater.exe).

• IT Admin Manual Testing or Troubleshooting: SOC or IT admins may manually run silent