VxMTEnonencrypted

Hunt Hypothesis

This detection identifies potentially malicious or sensitive data transfers occurring over unencrypted channels within the environment, signaling a risk of interception by adversaries monitoring network traffic. Proactively hunting for this behavior in Azure Sentinel is essential to uncover hidden exposure of critical assets and enforce stricter encryption policies before sensitive information is compromised during transit.

YARA Rule

rule VxMTEnonencrypted
{
      meta:
		author="malware-lu"
strings:
		$a0 = { F7 D9 80 E1 FE 75 02 49 49 97 A3 [2] 03 C1 24 FE 75 02 48 }

condition:
		$a0 at pe.entry_point
}

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 VxMTEnonencrypted detection rule, along with recommended filters and exclusions:

• Scenario: Microsoft Office Background Sync Services

  • Context: The Microsoft Office Click-to-Run Service (process name: OfficeClickToRun.exe) or OneDrive sync client (OneDrive.exe) frequently initiates unencrypted HTTP connections to legacy update servers or internal file shares during peak business hours. These processes often spawn child threads that the YARA rule flags as non-compliant due to the lack of TLS 1.2+ enforcement on specific internal endpoints.
  • Filter/Exclusion: Add a process name exclusion for OfficeClickToRun.exe and OneDrive.exe running under the SYSTEM or logged-in user context, specifically when connecting to IP ranges within the corporate DMZ (e.g., 10.x.x.x).

• Scenario: Legacy Internal Reporting Dashboard Access

  • Context: The internal business intelligence tool Tableau Server or a custom Power BI Report Server often serves static assets and initial handshake requests over HTTP before upgrading to HTTPS. When the w3wp.exe (IIS Worker Process) hosting these services communicates with older on-premise SQL Reporting Services, it triggers the rule due to unencrypted traffic between trusted internal zones.
  • Filter/Exclusion: Exclude traffic where the destination port is 80 and the source process is w3wp.exe, provided the destination IP belongs to the “Internal-Apps” security group defined in the firewall policy.

• Scenario: Scheduled Antivirus Definition Updates

  • Context: The Symantec Endpoint Protection or CrowdStrike Falcon agents perform scheduled definition updates early morning (e.g., 02:00 AM). During this window,