Generic rule for MacGyver.cap

Hunt Hypothesis

Adversaries may use the MacGyver.cap tool to execute arbitrary code or manipulate system resources, leveraging its capabilities for persistence or evasion. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify potential compromise and mitigate advanced threats that evade traditional detection methods.

YARA Rule

rule MacGyverCap : MacGyver
{
    meta:
        description = "Generic rule for MacGyver.cap"
        author = "[email protected]"
        date = "2021-05-11"
        reference = "https://github.com/fboldewin/MacGyver-s-return---An-EMV-Chip-cloning-case/blob/master/MacGyver's%20return%20-%20An%20EMV%20Chip%20cloning%20case.pdf"
        // May only the challenge guide you
		hash1 = "9dc70002e82c78ee34c813597925c6cf8aa8d68b7e9ce5bcc70ea9bcab9dbf4a"		
    strings:
        $string1 = "src/MacGyver/javacard/Header.cap" ascii wide
        $string2 = "src/MacGyver/javacard/Directory.cap" ascii wide
		$string3 = "src/MacGyver/javacard/Applet.cap" ascii wide
		$string4 = "src/MacGyver/javacard/Import.cap" ascii wide
		$string5 = "src/MacGyver/javacard/ConstantPool.cap" ascii wide
		$string6 = "src/MacGyver/javacard/Class.cap" ascii wide
		$string7 = "src/MacGyver/javacard/Method.cap" ascii wide
    condition:  
         all of them
}

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 7 string patterns in its detection logic.

References

False Positive Guidance

Scenario: A system administrator is using macgyver.cap to analyze network traffic for security audits.
Filter/Exclusion: Add a filter for process.name = "macgyver.cap" and user.name = "admin" or user.name = "security_team".
Scenario: A scheduled job runs macgyver.cap as part of a regular system health check or log analysis.
Filter/Exclusion: Exclude events where process.command_line contains "--scheduled" or "--job-id".
Scenario: A developer is using macgyver.cap to debug a custom application or network protocol.
Filter/Exclusion: Exclude events where process.user is a developer account (e.g., user.name = "dev_user") and process.command_line includes "--debug".
Scenario: A security tool like OSSEC or Snort is configured to use macgyver.cap for packet capture and analysis.
Filter/Exclusion: Exclude events where process.parent.name is ossec or snort, or where process.command_line includes "--tool".
Scenario: A system update or patching tool (e.g., Ansible or Chef) temporarily uses macgyver.cap to capture network behavior during deployment.
Filter/Exclusion: Exclude events where process.parent.name is ansible or chef, or where process.command_line includes "--patch" or "--update".