Apex30alpha500mhz

Hunt Hypothesis

This hunt hypothesis targets potential low-severity file-based anomalies identified by the Apex30alpha500mhz YARA signature to uncover early-stage adversary activity that may evade standard high-priority alerts. Proactive hunting for this specific pattern in Azure Sentinel is essential to validate false positives and detect subtle indicators of compromise before they escalate into significant security incidents.

YARA Rule

rule Apex30alpha500mhz
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 5F B9 14 00 00 00 51 BE 00 10 40 00 B9 00 [2] 00 8A 07 30 06 46 E2 FB 47 59 E2 EA 68 [3] 00 C3 }

condition:
		$a0
}

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 4 specific false positive scenarios for the Apex30alpha500mhz detection rule, including suggested filters and exclusions tailored for an enterprise environment:

• Scenario: Scheduled Antivirus Definition Updates via Microsoft Defender

  • Context: The YARA rule may flag the MpCmdRun.exe process when it downloads and installs new definition updates during off-hours. This activity often involves memory scanning patterns that mimic the signature of the Apex30alpha500mhz threat.
  • Filter/Exclusion: Configure an exclusion for the file path C:\Program Files\Microsoft Defender Antivirus\Platform\4.18.xxxx\MpCmdRun.exe and exclude any processes spawned by this parent where the command line contains “Update” or “Scan”.

• Scenario: Automated Backup Jobs Executed by Veeam Backup & Replication

  • Context: During nightly backup windows, the Veeam.Backup.Service.exe process performs intensive file I/O and memory mapping operations. The rule might misinterpret these high-volume data movements as suspicious behavior associated with the Apex30alpha500mhz logic.
  • Filter/Exclusion: Create a whitelist for the service account DOMAIN\VeeamBackupSvc and exclude all events where the parent process name is Veeam.Backup.Service.exe running on backup servers (e.g., hostnames matching *-BKP-*).

• Scenario: Endpoint Configuration Management via SCCM/MECM Application Deployment

  • Context: When System Center Configuration Manager deploys new applications or patches, the ccmsetup.exe and WUAHandler.exe processes execute scripts that modify registry keys and inject memory modules. These actions can trigger the YARA rule’s specific heuristic for “Apex30alpha500mhz”.