TMTPascalv040

Hunt Hypothesis

This rule detects the presence of the TMTPascalv040 YARA signature, which identifies specific malicious code patterns often associated with targeted intrusions or custom implant deployments. Proactively hunting for this signature allows the SOC team to uncover hidden footholds or dormant backdoors in Azure Sentinel environments before they are leveraged for lateral movement or data exfiltration.

YARA Rule

rule TMTPascalv040
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 0E 1F 06 8C 06 [2] 26 A1 [2] A3 [2] 8E C0 66 33 FF 66 33 C9 }

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

• Legacy Pascal-Based Utility Execution: An enterprise IT team deploys a custom, internally developed utility written in Delphi or Free Pascal (e.g., ConfigSync.exe) to standardize registry settings across the domain. This binary may contain specific Pascal compiler signatures or string constants that match the TMTPascalv040 YARA rule.

  • Filter/Exclusion: Exclude files located in the specific deployment directory (e.g., C:\Program Files\CorpTools\) or add an exclusion for the specific SHA-256 hash of the known-good utility.

• Antivirus/Endpoint Protection Engine Updates: The endpoint protection agent (e.g., CrowdStrike, SentinelOne, or Microsoft Defender) updates its heuristic engine or drops a temporary scan module written in Pascal to perform a deep memory scan. The temporary executable or DLL may trigger the rule during the update or scan process.

  • Filter/Exclusion: Exclude processes or files owned by the specific antivirus service account (e.g., svc-crowdstrike or MSPSVC) or exclude paths under the vendor’s installation directory (e.g., C:\Program Files\CrowdStrike Falcon\).

• Scheduled Backup or Archive Tool: A scheduled task runs a legacy backup tool (e.g., a custom wrapper for 7-Zip or a proprietary archive utility) that is compiled with a Pascal-based scripting layer or uses a Pascal-derived helper executable to manage compression tasks. The helper binary may match the YARA signature.

  • Filter/Exclusion: Exclude the specific scheduled task name (e.g., DailyBackupJob) or the path where the backup tool resides (e.g., C:\Scripts\Backup\), ensuring the exclusion is scoped to the specific executable name (e.g., ArchiveHelper.exe).

• Development Environment Build Artifacts: A developer on