Powershell Defender Exclusion

Severity: medium
Author: Florian Roth (Nextron Systems)
Source: upstream

Detects requests to exclude files, folders or processes from Antivirus scanning using PowerShell cmdlets

MITRE ATT&CK coverage

Tactic	Techniques
Defense Evasion	`T1562.001` Impair Defenses: Disable or Modify Tools

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation
Security-Auditing	4688	A new process has been created.

Stages and Predicates

Stage 1: `all of selection1`

or:
CommandLine|contains: 'Add-MpPreference '
CommandLine|contains: 'Set-MpPreference '

Stage 2: `all of selection2`

or:
CommandLine|contains: ' -ExclusionExtension '
CommandLine|contains: ' -ExclusionIpAddress '
CommandLine|contains: ' -ExclusionPath '
CommandLine|contains: ' -ExclusionProcess '

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
`CommandLine`	match	`-ExclusionExtension` `-ExclusionIpAddress` `-ExclusionPath` `-ExclusionProcess` `Add-MpPreference` corpus 3 (sigma 3) `Set-MpPreference` corpus 3 (sigma 3)