Powershell Defender Exclusion — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems). Source status: test; severity: medium. Source dates: 2021-04-29 / 2022-05-12.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 79e0cd5fe180cd16dda6eea0ff145c3623d9d396dfeae3d865e1a83d766ccc43

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: Powershell Defender Exclusion
id: 17769c90-230e-488b-a463-e05c08e9d48f
related:
    - id: c1344fa2-323b-4d2e-9176-84b4d4821c88
      type: similar
status: test
description: Detects requests to exclude files, folders or processes from Antivirus scanning using PowerShell cmdlets
references:
    - https://learn.microsoft.com/en-us/defender-endpoint/configure-process-opened-file-exclusions-microsoft-defender-antivirus
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1562.001/T1562.001.md
    - https://twitter.com/AdamTheAnalyst/status/1483497517119590403
author: Florian Roth (Nextron Systems)
date: 2021-04-29
modified: 2022-05-12
tags:
    - attack.defense-impairment
    - attack.t1685
logsource:
    category: process_creation
    product: windows
detection:
    selection1:
        CommandLine|contains:
            - 'Add-MpPreference '
            - 'Set-MpPreference '
    selection2:
        CommandLine|contains:
            - ' -ExclusionPath '
            - ' -ExclusionExtension '
            - ' -ExclusionProcess '
            - ' -ExclusionIpAddress '
    condition: all of selection*
falsepositives:
    - Possible Admin Activity
    - Other Cmdlets that may use the same parameters
level: medium

Original YAML and metadata in JSON

False positives

• Possible Admin Activity
• Other Cmdlets that may use the same parameters

Source references

• https://learn.microsoft.com/en-us/defender-endpoint/configure-process-opened-file-exclusions-microsoft-defender-antivirus
• https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1562.001/T1562.001.md
• https://twitter.com/AdamTheAnalyst/status/1483497517119590403