tElock098tE

Hunt Hypothesis

This detection identifies potential malicious file execution or persistence mechanisms characterized by the specific signature pattern of the tElock098tE YARA rule within Azure Sentinel workloads. Proactive hunting for this behavior is essential to uncover early-stage threats that may evade standard alerting thresholds, allowing the SOC team to investigate low-severity anomalies before they escalate into significant security incidents.

YARA Rule

rule tElock098tE
{
      meta:
		author="malware-lu"
strings:
		$a0 = { E9 25 E4 FF FF 00 00 00 [4] 1E [2] 00 00 00 00 00 00 00 00 00 3E [2] 00 2E [2] 00 26 [2] 00 00 00 00 00 00 00 00 00 4B [2] 00 36 [2] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 56 [2] 00 00 00 00 00 69 [2] 00 00 00 00 00 56 [2] 00 00 00 00 00 69 [2] 00 00 00 00 00 6B 65 72 6E 65 6C 33 32 2E 64 6C 6C 00 75 73 65 }

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 tElock098tE detection rule, including suggested filters and exclusions:

• Scenario: Automated Patch Deployment via SCCM/Intune

  • Context: During scheduled maintenance windows, Microsoft Endpoint Configuration Manager (SCCM) or Intune pushes cumulative updates to endpoints. The update installer (WindowsUpdate.exe or msiexec) often extracts temporary binaries that match the tElock098tE signature pattern before installation completes.
  • Filter/Exclusion: Create a whitelist for the process path C:\Program Files (x86)\Microsoft Intune Management Extension\IntuneManagementExtension.exe and its child processes. Additionally, exclude alerts occurring between 02:00 and 04:00 on Tuesdays and Thursids where the parent process is ccmsetup.exe.

• Scenario: Antivirus On-Access Scanning of Large Archives

  • Context: When users or backup agents (e.g., Veeam, Commvault) move large .zip or .tar.gz files containing embedded scripts through the file system, the real-time scanner (e.g., CrowdStrike Falcon or SentinelOne) may trigger a heuristic scan that mimics the behavior of the tElock098tE rule.
  • Filter/Exclusion: Exclude alerts where the parent process is falcon.sys (CrowdStrike) or sone.exe (SentinelOne) and the file extension is .zip, .7z, or .gz. Implement a logic check to ignore events if the file size exceeds 50MB, as legitimate archives are typically large.

• Scenario: CI/CD Pipeline Artifact Extraction

  • Context: In DevOps environments, Jenkins or GitHub Actions runners frequently extract build artifacts (J