Potential DLL Sideloading Of MsCorSvc.DLL — Sigma Rule

Rule metadata and linked tags

Author: Wietze Beukema. Source status: test; severity: medium. Source dates: 2024-07-11 / 2025-02-26.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: ef979487444b798eeb48d1ffd9a168993f5ab7600072fb2d5be92a94f613a24e

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: Potential DLL Sideloading Of MsCorSvc.DLL
id: cdb15e19-c2d0-432a-928e-e49c8c60dcf2
status: test
description: Detects potential DLL sideloading of "mscorsvc.dll".
references:
    - https://hijacklibs.net/entries/microsoft/built-in/mscorsvc.html
author: Wietze Beukema
date: 2024-07-11
modified: 2025-02-26
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.execution
    - attack.stealth
    - attack.t1574.001
logsource:
    product: windows
    category: image_load
detection:
    selection:
        ImageLoaded|endswith: '\mscorsvc.dll'
    filter_main_generic:
        ImageLoaded|startswith:
            - 'C:\Windows\Microsoft.NET\Framework\'
            - 'C:\Windows\Microsoft.NET\Framework64\'
            - 'C:\Windows\Microsoft.NET\FrameworkArm\'
            - 'C:\Windows\Microsoft.NET\FrameworkArm64\'
            - 'C:\Windows\WinSxS\'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Legitimate applications loading their own versions of the DLL mentioned in this rule.
level: medium

Original YAML and metadata in JSON

False positives

• Legitimate applications loading their own versions of the DLL mentioned in this rule.

Source references

• https://hijacklibs.net/entries/microsoft/built-in/mscorsvc.html