Potential DLL Sideloading Of MsCorSvc.DLL

Severity: medium
Author: Wietze Beukema
Source: upstream

Detects potential DLL sideloading of "mscorsvc.dll".

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1574.001` Hijack Execution Flow: DLL
Privilege Escalation	`T1574.001` Hijack Execution Flow: DLL
Defense Evasion	`T1574.001` Hijack Execution Flow: DLL

Event coverage

Provider	Event ID	Title
Sysmon	7	Image loaded

Stages and Predicates

Stage 1: `selection`

ImageLoaded|endswith: '\mscorsvc.dll'

Stage 2: `not 1 of filter_main_generic`

or:
ImageLoaded|startswith: 'C:\Windows\Microsoft.NET\Framework64\'
ImageLoaded|startswith: 'C:\Windows\Microsoft.NET\FrameworkArm64\'
ImageLoaded|startswith: 'C:\Windows\Microsoft.NET\FrameworkArm\'
ImageLoaded|startswith: 'C:\Windows\Microsoft.NET\Framework\'
ImageLoaded|startswith: '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	`\mscorsvc.dll`
`ImageLoaded`	starts_with	`C:\Windows\Microsoft.NET\Framework64\` `C:\Windows\Microsoft.NET\FrameworkArm64\` `C:\Windows\Microsoft.NET\FrameworkArm\` `C:\Windows\Microsoft.NET\Framework\` `C:\Windows\WinSxS\` corpus 9 (sigma 9)