MEGALITEv120a

Hunt Hypothesis

This detection identifies potential file-based threats or specific malware signatures captured by the MEGALITEv120a YARA rule within the Azure Sentinel environment. Proactive hunting for this indicator is essential to uncover early-stage infections that may not yet trigger high-severity alerts, allowing the SOC team to investigate and contain low-level anomalies before they escalate into broader incidents.

YARA Rule

rule MEGALITEv120a
{
      meta:
		author="malware-lu"
strings:
		$a0 = { B8 [2] BA [2] 05 [2] 3B 2D 73 ?? 72 ?? B4 09 BA [2] CD 21 CD 90 }

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 MEGALITEv120a detection rule, formatted with actionable filters and exclusions:

• Scenario: Legitimate execution of Microsoft Office Click-to-Run updates.

  • Context: The OfficeClickToRun.exe process frequently spawns child processes to download and install patches, which often match the YARA signature for MEGALITE due to its modular update architecture.
  • Filter/Exclusion: Exclude any process where the parent image is C:\Program Files\Microsoft Office Click-to-Run\OfficeClickToRun.exe AND the command line contains /update.

• Scenario: Scheduled Windows Defender Antivirus real-time scanning.

  • Context: The MsMpEng.exe service performs periodic deep scans that load various signature modules, triggering the rule when specific heuristic patterns within the antivirus engine are loaded into memory.
  • Filter/Exclusion: Create a filter to ignore events where the process name is MsMpEng.exe running under the SYSTEM account with a high integrity level (e.g., IntegrityLevel == 'System').

• Scenario: Deployment of enterprise-wide Group Policy updates via SCCM.

  • Context: System Center Configuration Manager (SCCM) uses the ccmsetup.exe or WUAHandler.exe to push policy changes, which often instantiate temporary worker processes that mimic the behavioral footprint of MEGALITE.
  • Filter/Exclusion: Exclude events where the parent process is CcmExec.exe and the execution path resides within C:\Windows\CCM\.

• Scenario: Automated backup jobs utilizing Veeam Agent for Windows.

  • Context: During scheduled backup windows, VeeamAgentService.exe launches multiple worker threads to compress data streams