ReflexiveArcadeWrapper

Hunt Hypothesis

This detection targets adversary behavior involving the execution of reflexive arcade wrapper processes, which often indicate early-stage fileless malware or obfuscated payload delivery techniques designed to evade static analysis. A SOC team should proactively hunt for this activity in Azure Sentinel because these low-severity signals frequently represent initial footholds that can escalate into significant lateral movement campaigns if not identified and investigated during the reconnaissance phase.

YARA Rule

rule ReflexiveArcadeWrapper
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 98 68 42 00 68 14 FA 41 00 64 A1 00 00 00 00 50 64 89 25 00 00 00 00 83 EC 58 53 56 57 89 65 E8 FF 15 F8 50 42 00 33 D2 8A D4 89 15 3C E8 42 00 8B C8 81 E1 FF 00 00 00 89 0D 38 E8 42 00 C1 E1 08 03 CA 89 0D 34 E8 42 00 C1 E8 10 A3 30 E8 }

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 ReflexiveArcadeWrapper detection rule in an enterprise environment, along with suggested filters and exclusions:

• Scenario: Microsoft Defender for Endpoint Self-Protection Updates

  • Context: The Windows Security service (SecurityHealthAgent.exe) frequently launches a reflexive wrapper process to apply real-time definition updates or perform self-healing checks. This behavior mimics the signature of an arcade wrapper often used by EDR solutions to isolate processes.
  • Filter/Exclusion: Exclude processes where ImageFileName is SecurityHealthAgent.exe AND the parent process is svchost.exe. Additionally, filter out events occurring on port 443 during scheduled update windows (e.g., 02:00–04:00 daily).

• Scenario: CrowdStrike Falcon Sensor Real-Time Monitoring

  • Context: The CrowdStrike Falcon sensor (csfalcon.exe) utilizes a reflexive wrapper mechanism to monitor its own child processes and enforce policy enforcement. When the sensor scans its own execution context, it triggers the ReflexiveArcadeWrapper signature due to the nested process structure.
  • Filter/Exclusion: Create an exclusion rule for any event where the parent process path contains \Program Files\CrowdStrike\ and the child process name matches csfalcon.exe.

• Scenario: Scheduled SCCM (MECM) Application Deployment

  • Context: During a scheduled System Center Configuration Manager deployment, the ccmexec.exe service often wraps application installers within a temporary reflexive container to ensure integrity and logging. This is common when deploying line-of-business applications to thousands of endpoints simultaneously.
  • Filter/Exclusion: Exclude events where the parent process is ccmexec.exe and the execution time falls within the defined maintenance window