AHTeamEPProtector03fakeVOBProtectCDFEUERRADER

Hunt Hypothesis

This detection identifies potential adversary activity involving fake Volume Object Block (VOB) protection mechanisms that may indicate an attempt to evade endpoint security controls or establish persistence through deceptive file structures. A SOC team should proactively hunt for this behavior in Azure Sentinel to uncover stealthy initial access or lateral movement tactics that traditional signature-based defenses might overlook due to their low severity and specialized YARA rule nature.

YARA Rule

rule AHTeamEPProtector03fakeVOBProtectCDFEUERRADER
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 90 [46] 90 FF E0 5F 81 EF 00 00 00 00 BE 00 00 40 00 8B 87 00 00 00 00 03 C6 57 56 8C A7 00 00 00 00 FF 10 89 87 00 00 00 00 5E 5F }

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 4 specific false positive scenarios for the AHTeamEPProtector03fakeVOBProtectCDFEUERRADER detection rule, tailored for a legitimate enterprise environment:

• Scenario: Enterprise Antivirus Scheduled Scans

  • Context: The rule triggers when major endpoint protection suites (e.g., Microsoft Defender for Endpoint, CrowdStrike Falcon, or Symantec Endpoint Protection) perform their daily scheduled “On-Demand” scan. These tools often generate temporary virtual objects or cache files in the C:\ProgramData or %TEMP% directories that mimic the signature of a fake VOB (Virtual Object Block) protector being read by an external process.
  • Suggested Filter: Exclude processes belonging to known EDR/Antivirus services (e.g., MsMpEng.exe, FalconSensor.exe, Symantec Endpoint Protection Client) when they are accessing files under the %ProgramData% or %TEMP% directories during their configured maintenance windows.

• Scenario: Microsoft Office 365 Click-to-Run Updates

  • Context: During background update cycles, the Microsoft Office Click-to-Run service (OfficeClickToRun.exe) creates temporary installer packages and reads configuration manifests that resemble the “fake VOB” structure detected by the YARA rule. This is common in environments where auto-updates are enabled for all users.
  • Suggested Filter: Create an exclusion based on the process name OfficeClickToRun.exe (and its child processes like setup.exe) specifically when the accessed file path contains keywords such as \Microsoft Office\, \ClickToRun\, or .msi.

• Scenario: System Backup and Archiving Jobs

  • Context: Enterprise backup solutions like Veeam Agent, Commvault, or Acronis Cyber Protect often utilize a ”