VxAugust16thIronMaiden

Hunt Hypothesis

This detection identifies potential malicious activity associated with the “VxAugust16thIronMaiden” signature, which may indicate early-stage file-based threats or specific malware variants within the environment. Proactively hunting for this behavior in Azure Sentinel allows the SOC team to validate low-severity alerts against actual threat intelligence and uncover hidden indicators of compromise before they escalate into significant incidents.

YARA Rule

rule VxAugust16thIronMaiden
{
      meta:
		author="malware-lu"
strings:
		$a0 = { BA 79 02 03 D7 B4 1A CD 21 B8 24 35 CD 21 5F 57 89 9D 4E 02 8C 85 50 02 }

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 VxAugust16thIronMaiden detection rule, including suggested filters and exclusions:

• Scenario: The Microsoft Office 365 ProPlus Click-to-Run (C2R) update service (OfficeClickToRun.exe) executes a background process to apply security patches or feature updates. This often involves spawning child processes that load scripts matching the Iron Maiden signature, particularly when updating the “Iron” component of the Office suite.

  • Suggested Filter: Exclude the specific parent process path C:\Program Files\Microsoft Office ClickToRun\OfficeClickToRun.exe and its immediate children where the file hash matches known Microsoft-signed binaries.

• Scenario: A scheduled System Center Configuration Manager (SCCM) task sequence runs during business hours to deploy a new application package or perform a compliance check. The deployment agent (ccmexec.exe) invokes PowerShell scripts that instantiate temporary executables, triggering the rule due to script execution patterns similar to the detection logic.

  • Suggested Filter: Create an exclusion for processes spawned by C:\Windows\CCM\ccmexec.exe where the command line contains keywords like “TaskSequence” or “Deployment”, and limit the scope to the specific SCCM site server IP range.

• Scenario: The enterprise CrowdStrike Falcon endpoint protection agent performs a scheduled deep scan or updates its definition database. During this process, the csfalcon.exe service launches auxiliary modules that interact with system memory in a way that mimics the behavioral signature of the VxAugust16thIronMaiden rule.

  • Suggested Filter: Whitelist the CrowdStrike Falcon Agent executable (C:\Program Files\CrowdStrike\Falcon\csfalcon.exe) and its associated worker processes, ensuring the exclusion applies only when the process is