Process Creation Using Sysnative Folder — Sigma Rule

Rule metadata and linked tags

Author: Max Altgelt (Nextron Systems). Source status: test; severity: medium. Source dates: 2022-08-23 / 2025-10-08.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 7ef2b8359200bba49e112e7e6867a99f1ddfdcf9e60b433f76280bf406db460d

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Process Creation Using Sysnative Folder
id: 3c1b5fb0-c72f-45ba-abd1-4d4c353144ab
status: test
description: Detects process creation events that use the Sysnative folder (common for CobaltStrike spawns)
references:
    - https://thedfirreport.com/2021/08/29/cobalt-strike-a-defenders-guide/
author: Max Altgelt (Nextron Systems)
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

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://thedfirreport.com/2021/08/29/cobalt-strike-a-defenders-guide/