DotNet CLR DLL Loaded By Scripting Applications — Sigma Rule

Rule metadata and linked tags

Author: omkar72, oscd.community. Source status: test; severity: high. Source dates: 2020-10-14 / 2023-02-23.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: d4607e1f2e0bba95511bed9a6cdeb32242943f73a9c10388f9d99f67669f0038

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: DotNet CLR DLL Loaded By Scripting Applications
id: 4508a70e-97ef-4300-b62b-ff27992990ea
status: test
description: Detects .NET CLR DLLs being loaded by scripting applications such as wscript or cscript. This could be an indication of potential suspicious execution.
references:
    - https://github.com/tyranid/DotNetToJScript
    - https://thewover.github.io/Introducing-Donut/
    - https://web.archive.org/web/20230329154538/https://blog.menasec.net/2019/07/interesting-difr-traces-of-net-clr.html
    - https://web.archive.org/web/20221026202428/https://gist.github.com/code-scrap/d7f152ffcdb3e0b02f7f394f5187f008
author: omkar72, oscd.community
date: 2020-10-14
modified: 2023-02-23
tags:
    - attack.execution
    - attack.privilege-escalation
    - attack.stealth
    - attack.t1055
logsource:
    category: image_load
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmstp.exe'
            - '\cscript.exe'
            - '\mshta.exe'
            - '\msxsl.exe'
            - '\regsvr32.exe'
            # - '\svchost.exe'
            - '\wmic.exe'
            - '\wscript.exe'
        ImageLoaded|endswith:
            - '\clr.dll'
            - '\mscoree.dll'
            - '\mscorlib.dll'
    condition: selection
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://github.com/tyranid/DotNetToJScript
• https://thewover.github.io/Introducing-Donut/
• https://web.archive.org/web/20230329154538/https://blog.menasec.net/2019/07/interesting-difr-traces-of-net-clr.html
• https://web.archive.org/web/20221026202428/https://gist.github.com/code-scrap/d7f152ffcdb3e0b02f7f394f5187f008