Detection rules › Sigma
Potential DLL Sideloading Of MsCorSvc.DLL
Detects potential DLL sideloading of "mscorsvc.dll".
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Execution | T1574.001 Hijack Execution Flow: DLL |
| Stealth | T1574.001 Hijack Execution Flow: DLL |
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 7 | Image loaded |
Rule body yaml
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
Stages and Predicates
Stage 0: condition
selection and not 1 of filter_main_*Stage 1: selection
selection:
ImageLoaded|endswith: '\mscorsvc.dll'
Stage 2: not filter_main_generic
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\'
Exclusions
Top-level NOT(...) conjuncts: predicates this rule actively suppresses.
| Field | Kind | Excluded values |
|---|---|---|
ImageLoaded | starts_with | C:\Windows\Microsoft.NET\Framework64\ |
ImageLoaded | starts_with | C:\Windows\Microsoft.NET\FrameworkArm64\ |
ImageLoaded | starts_with | C:\Windows\Microsoft.NET\FrameworkArm\ |
ImageLoaded | starts_with | C:\Windows\Microsoft.NET\Framework\ |
ImageLoaded | starts_with | C:\Windows\WinSxS\ |
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
ImageLoaded | ends_with |
|