Pohernah103byKas

Hunt Hypothesis

This hunt hypothesis targets potential malware or suspicious artifacts identified by the “Pohernah103byKas” YARA signature to uncover stealthy adversary activity that may not trigger high-severity alerts due to its current low severity classification. Proactively hunting for this behavior in Azure Sentinel allows the SOC team to validate false positives, refine detection logic, and identify early-stage threats before they escalate into significant incidents.

YARA Rule

rule Pohernah103byKas
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 60 E8 00 00 00 00 5D 81 ED 2A 27 40 00 31 C0 40 83 F0 06 40 3D 40 1F 00 00 75 07 BE 6A 27 40 00 EB 02 EB EB 8B 85 9E 28 40 00 83 F8 01 75 17 31 C0 01 EE 3D 99 00 00 00 74 0C 8B 8D 86 28 40 00 30 0E 40 46 EB ED [153] 56 57 4F F7 D7 21 FE 89 F0 5F 5E C3 60 83 F0 05 40 90 48 83 F0 05 89 C6 89 D7 60 E8 0B 00 00 00 61 83 C7 08 83 E9 07 E2 F1 61 C3 57 8B 1F 8B 4F 04 68 B9 79 37 9E 5A 42 89 D0 48 C1 E0 05 BF 20 00 00 00 4A 89 DD C1 E5 04 29 E9 8B 6E 08 31 DD 29 E9 89 DD C1 ED 05 31 C5 29 E9 2B 4E 0C 89 CD C1 E5 04 29 EB 8B 2E 31 CD 29 EB 89 CD C1 ED 05 31 C5 29 EB 2B 5E 04 29 D0 4F 75 C8 5F 89 1F 89 4F 04 C3 }

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 Pohernah103byKas YARA rule detection logic, including targeted filters and exclusions:

• Antivirus Engine Scanning of Compressed Archives

  • Scenario: The endpoint protection suite (e.g., CrowdStrike Falcon or Microsoft Defender) scans large .zip or .7z archives containing software installers in the C:\Temp\Downloads directory. The YARA rule triggers because it detects specific byte sequences within the compressed payload that mimic the signature of the targeted malware, even though the file is benign.
  • Filter/Exclusion: Exclude processes matching C:\Program Files\CrowdStrike\FalconSensor\csfalcon.exe or MsMpEng.exe when the target file path contains \Downloads\*.zip. Additionally, add a logic check to exclude alerts where the file extension is .7z and the process user context is SYSTEM.

• Scheduled Software Deployment via SCCM/Intune

  • Scenario: During nightly maintenance windows (02:00 – 04:00), System Center Configuration Manager (SCCM) or Microsoft Intune pushes a new application update to workstations. The deployment agent extracts binaries and executes them, triggering the rule due to the presence of specific code patterns in the installer executable that overlap with the YARA signature.
  • Filter/Exclusion: Create an exclusion for process names ccmsetup.exe (SCCM) or Microsoft.IntuneManagementAgent.exe. Apply a time-based filter to suppress alerts generated between 01:00 and 05:00 local time on weekdays, as these are known maintenance windows.

• DevOps Build Pipeline Artifact Generation

  • Scenario: In the R&D department, Jenkins or Azure DevOps agents running on build