Windows Process Creation Using the Sysnative Directory Path

Alerts on process executions referencing \Windows\Sysnative, excluding common ngen.exe and a known XAMPP bat launcher.

FreeReviewedSigma · Medium · v1

Product: windows
Category: process_creation
Author: Max Altgelt (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2022-08-23
Updated: 2026-07-30

ATT&CK techniques

Priv Esc → Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
- T1055Process Injection
Defense Evasion
- T1055Process Injection
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags Windows process creation events where the process command line or image path contains the \Windows\Sysnative directory. Attackers can use Sysnative to access the native 64-bit system path from a 32-bit context, helping with evasion and stealth. It relies on process creation telemetry, matching the Image and CommandLine fields for the Sysnative path while excluding likely benign .NET ngen.exe activity and a specific XAMPP startup pattern.

Reporting behind it

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Windows Process Creation Using the Sysnative Directory Path

Pivot detection · T1055 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

windows-process-creation-using-the-sysnative-directory-path-3c1b5fb0

title: Windows Process Creation Using the Sysnative Directory Path
id: 8e64ccb0-9b0f-4e18-b41d-211fd0bfdd91
status: test
description: This rule flags Windows process creation events where the process command line or image path contains the \Windows\Sysnative directory. Attackers can use Sysnative to access the native 64-bit system path from a 32-bit context, helping with evasion and stealth. It relies on process creation telemetry, matching the Image and CommandLine fields for the Sysnative path while excluding likely benign .NET ngen.exe activity and a specific XAMPP startup pattern.
references:
  - https://thedfirreport.com/2021/08/29/cobalt-strike-a-defenders-guide/
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_susp_sysnative.yml
author: Max Altgelt (Nextron Systems), Huntrule Team
date: 2022-08-23
modified: 2025-10-08
tags:
  - attack.privilege-escalation
  - attack.stealth
  - attack.t1055
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    - CommandLine|contains: :\Windows\Sysnative\
    - Image|contains: :\Windows\Sysnative\
  filter_main_ngen:
    Image|contains:
      - C:\Windows\Microsoft.NET\Framework64\v
      - C:\Windows\Microsoft.NET\Framework\v
      - C:\Windows\Microsoft.NET\FrameworkArm\v
      - C:\Windows\Microsoft.NET\FrameworkArm64\v
    Image|endswith: \ngen.exe
    CommandLine|contains: install
  filter_optional_xampp:
    CommandLine|contains|all:
      - '"C:\Windows\sysnative\cmd.exe"'
      - \xampp\
      - \catalina_start.bat
  condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
  - Unknown
level: medium
license: DRL-1.1
related:
  - id: 3c1b5fb0-c72f-45ba-abd1-4d4c353144ab
    type: derived

Convert

This rule as a query you can run. Uses no unlock credit.

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