tElockv071

Hunt Hypothesis

This detection identifies potential file-based threats or specific malware signatures identified by the tElockv071 YARA rule within Azure Sentinel’s endpoint telemetry. Although currently classified as low severity, proactive hunting for this signature is essential to uncover early-stage infections that may evade standard threshold-based alerts and prevent lateral movement before escalation.

YARA Rule

rule tElockv071
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 60 E8 ED 10 00 00 C3 83 }

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 tElockv071 detection rule, including suggested filters and exclusions:

• Scenario: Automated Endpoint Protection Scans

  • Context: Enterprise-grade antivirus solutions (e.g., CrowdStrike Falcon, Microsoft Defender for Endpoint) perform periodic real-time scans or scheduled on-access checks. These tools often inject code into running processes to analyze memory, which can mimic the behavior patterns detected by tElockv071 as a potential locking mechanism attack.
  • Filter/Exclusion: Create an exclusion rule based on the process image path for known security agents.
    • Example: Exclude alerts where Process.ImagePath contains \Program Files\CrowdStrike\ or \Windows\System32\MsMpEng.exe.

• Scenario: Scheduled Backup and Encryption Jobs

  • Context: Automated backup solutions (e.g., Veeam, Commvault) or enterprise encryption tools (e.g., Microsoft BitLocker Management Service) trigger scheduled tasks that lock files during the encryption or snapshot process. The YARA rule may interpret these file locking events as suspicious activity.
  • Filter/Exclusion: Filter out alerts generated by specific scheduled task names or service accounts known for backup operations.
    • Example: Exclude where Process.CommandLine contains “VeeamBackup.exe” and the user context is a dedicated service account like DOMAIN\svc_backup_agent.

• Scenario: System Patching and Update Deployment

  • Context: During Windows Update cycles or mass patch deployments via tools like WSUS (Windows Server Update Services) or SCCM/MECM, the system locks configuration files and registry keys to apply changes. This high-volume locking activity often triggers tElockv071.