AHTeamEPProtector03fakeVIRUSIWormHybrisFEUERRADER

Hunt Hypothesis

This detection identifies adversary behavior involving the execution of a deceptive worm masquerading as an antivirus protector to evade initial scrutiny and establish persistence within endpoints. A SOC team should proactively hunt for this signature in Azure Sentinel because low-severity alerts often mask sophisticated social engineering attacks that could serve as a precursor to broader lateral movement or data exfiltration campaigns.

YARA Rule

rule AHTeamEPProtector03fakeVIRUSIWormHybrisFEUERRADER
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 90 [46] 90 FF E0 EB 16 A8 54 00 00 47 41 42 4C 4B 43 47 43 00 00 00 00 00 00 52 49 53 00 FC 68 4C 70 40 00 FF 15 }

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 detection rule AHTeamEPProtector03fakeVIRUSIWormHybrisFEUERRADER, along with targeted filters and exclusions:

• Antivirus Engine Self-Scanning

  • Scenario: The enterprise endpoint protection suite (e.g., Microsoft Defender, CrowdStrike Falcon, or Symantec Endpoint Protection) initiates a scheduled deep scan of its own installation directory. During this process, the AV engine’s scanning service (MsMpEng.exe or csfalcon.sys) reads its own definition update files and signature databases, which contain embedded signatures that mimic worm-like behavior patterns (recursive file reading and network probing).
  • Suggested Filter: Exclude the specific executable path of the EPP agent itself.
    • Example: Exclude Process: C:\Program Files\Microsoft Defender\MsMpEng.exe or C:\ProgramData\CrowdStrike\csfalcon\bin\csfalcon.exe.

• Hybrid Cloud Backup Agent Operations

  • Scenario: A scheduled backup job (e.g., Veeam, Rubrik, or Commvault) runs during off-hours to replicate data to a cloud repository. The backup agent (VeeamTransportService.exe or rubrik-agent) performs rapid file enumeration and checksum verification across the “Hybris” application directories. This high-volume I/O activity combined with network transmission of metadata can trigger the “Worm” logic in the YARA rule due to the pattern of sequential file access followed by immediate network communication.
  • Suggested Filter: Create an exclusion based on the backup service account and specific process names during maintenance windows.
    • Example: Exclude Process: VeeamTransportService.exe where User Account = DOMAIN\BackupSvc AND `Time Window = 01:00