NTkrnlSecureSuite01015NTkrnlSoftware

Hunt Hypothesis

This detection identifies potential kernel-level anomalies or unauthorized software modifications within the Windows environment by leveraging a specific YARA signature targeting NTkrnlSecureSuite components. The SOC team should proactively hunt for this behavior in Azure Sentinel to uncover stealthy persistence mechanisms that may evade traditional endpoint protections, ensuring early identification of sophisticated adversaries manipulating core system processes.

YARA Rule

rule NTkrnlSecureSuite01015NTkrnlSoftware
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 00 00 00 00 00 00 00 00 00 00 00 00 34 10 00 00 28 10 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [8] 00 00 00 00 4B 65 72 6E 65 6C 33 32 2E 64 6C 6C 00 00 00 4C 6F 61 64 4C 69 62 72 61 72 79 41 00 00 00 47 65 74 50 72 6F 63 41 64 64 72 65 73 73 00 68 [4] E8 01 00 00 00 C3 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 NTkrnlSecureSuite01015NTkrnlSoftware detection rule, including targeted filters and exclusions:

• Scenario: Scheduled Antivirus Definition Updates via Windows Update

  • Context: The ntkrnl.exe process often spawns child processes or interacts with system hooks when the Microsoft Defender or third-party EDR (e.g., CrowdStrike Falcon) performs a scheduled definition update. This activity can mimic the behavior of kernel-level software installation detected by the rule.
  • Filter/Exclusion: Exclude file paths containing C:\ProgramData\Microsoft\Windows Defender\ and process names matching *UpdateService.exe or MsMpEng.exe. Additionally, filter out events occurring during the configured maintenance window (e.g., 02:00–04:00 local time).

• Scenario: System Patch Deployment via SCCM/Intune

  • Context: During enterprise-wide patching cycles, tools like Microsoft Endpoint Configuration Manager (SCCM) or Intune execute kernel-level updates. The ntkrnl.exe process is actively involved in the installation of hotfixes and driver updates, which may trigger the YARA signature designed to detect new software registration.
  • Filter/Exclusion: Create a whitelist for command lines containing keywords such as wusa.exe, msiexec /i, or specific SCCM agent process names (ccmsetup.exe). Exclude events where the parent process is TaskHostW.exe running under the “System” account during known maintenance windows.

• Scenario: Real-Time Monitoring by Endpoint Detection and Response (EDR) Agents

  • Context: EDR agents like SentinelOne, Carbon Black, or Symantec Endpoint Protection often inject hooks into ntkrnl.exe to monitor system calls. When