Powershell Defender Disable Scan Feature — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems). Source status: test; severity: high. Source dates: 2022-03-03 / 2024-01-02.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 80b8041fa2117d205c851721f03e1f744b1dba94ff9e3d7b11dbdb850530076f

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 Disable Scan Feature
id: 1ec65a5f-9473-4f12-97da-622044d6df21
status: test
description: Detects requests to disable Microsoft Defender features using PowerShell commands
references:
    - https://learn.microsoft.com/en-us/powershell/module/defender/set-mppreference?view=windowsserver2022-ps
    - https://www.virustotal.com/gui/file/d609799091731d83d75ec5d1f030571af20c45efeeb94840b67ea09a3283ab65/behavior/C2AE
    - https://www.virustotal.com/gui/search/content%253A%2522Set-MpPreference%2520-Disable%2522/files
author: Florian Roth (Nextron Systems)
date: 2022-03-03
modified: 2024-01-02
tags:
    - attack.defense-impairment
    - attack.t1685
logsource:
    category: process_creation
    product: windows
detection:
    selection_cli_cmdlet:
        CommandLine|contains:
            - 'Add-MpPreference '
            - 'Set-MpPreference '
    selection_cli_option:
        CommandLine|contains:
            - 'DisableArchiveScanning '
            - 'DisableRealtimeMonitoring '
            - 'DisableIOAVProtection '
            - 'DisableBehaviorMonitoring '
            - 'DisableBlockAtFirstSeen '
            - 'DisableCatchupFullScan '
            - 'DisableCatchupQuickScan '
    selection_cli_value:
        CommandLine|contains:
            - '$true'
            - ' 1 '
    selection_encoded_modifier:
        CommandLine|base64offset|contains:
            # Note: Since this is calculating offsets casing is important
            - 'disablearchivescanning '
            - 'DisableArchiveScanning '
            - 'disablebehaviormonitoring '
            - 'DisableBehaviorMonitoring '
            - 'disableblockatfirstseen '
            - 'DisableBlockAtFirstSeen '
            - 'disablecatchupfullscan '
            - 'DisableCatchupFullScan '
            - 'disablecatchupquickscan '
            - 'DisableCatchupQuickScan '
            - 'disableioavprotection '
            - 'DisableIOAVProtection '
            - 'disablerealtimemonitoring '
            - 'DisableRealtimeMonitoring '
    selection_encoded_direct:
        CommandLine|contains:
            - 'RABpAHMAYQBiAGwAZQBSAGUAYQBsAHQAaQBtAGUATQBvAG4AaQB0AG8AcgBpAG4AZwAgA'
            - 'QAaQBzAGEAYgBsAGUAUgBlAGEAbAB0AGkAbQBlAE0AbwBuAGkAdABvAHIAaQBuAGcAIA'
            - 'EAGkAcwBhAGIAbABlAFIAZQBhAGwAdABpAG0AZQBNAG8AbgBpAHQAbwByAGkAbgBnACAA'
            - 'RABpAHMAYQBiAGwAZQBJAE8AQQBWAFAAcgBvAHQAZQBjAHQAaQBvAG4AIA'
            - 'QAaQBzAGEAYgBsAGUASQBPAEEAVgBQAHIAbwB0AGUAYwB0AGkAbwBuACAA'
            - 'EAGkAcwBhAGIAbABlAEkATwBBAFYAUAByAG8AdABlAGMAdABpAG8AbgAgA'
            - 'RABpAHMAYQBiAGwAZQBCAGUAaABhAHYAaQBvAHIATQBvAG4AaQB0AG8AcgBpAG4AZwAgA'
            - 'QAaQBzAGEAYgBsAGUAQgBlAGgAYQB2AGkAbwByAE0AbwBuAGkAdABvAHIAaQBuAGcAIA'
            - 'EAGkAcwBhAGIAbABlAEIAZQBoAGEAdgBpAG8AcgBNAG8AbgBpAHQAbwByAGkAbgBnACAA'
            - 'RABpAHMAYQBiAGwAZQBCAGwAbwBjAGsAQQB0AEYAaQByAHMAdABTAGUAZQBuACAA'
            - 'QAaQBzAGEAYgBsAGUAQgBsAG8AYwBrAEEAdABGAGkAcgBzAHQAUwBlAGUAbgAgA'
            - 'EAGkAcwBhAGIAbABlAEIAbABvAGMAawBBAHQARgBpAHIAcwB0AFMAZQBlAG4AIA'
            - 'ZABpAHMAYQBiAGwAZQByAGUAYQBsAHQAaQBtAGUAbQBvAG4AaQB0AG8AcgBpAG4AZwAgA'
            - 'QAaQBzAGEAYgBsAGUAcgBlAGEAbAB0AGkAbQBlAG0AbwBuAGkAdABvAHIAaQBuAGcAIA'
            - 'kAGkAcwBhAGIAbABlAHIAZQBhAGwAdABpAG0AZQBtAG8AbgBpAHQAbwByAGkAbgBnACAA'
            - 'ZABpAHMAYQBiAGwAZQBpAG8AYQB2AHAAcgBvAHQAZQBjAHQAaQBvAG4AIA'
            - 'QAaQBzAGEAYgBsAGUAaQBvAGEAdgBwAHIAbwB0AGUAYwB0AGkAbwBuACAA'
            - 'kAGkAcwBhAGIAbABlAGkAbwBhAHYAcAByAG8AdABlAGMAdABpAG8AbgAgA'
            - 'ZABpAHMAYQBiAGwAZQBiAGUAaABhAHYAaQBvAHIAbQBvAG4AaQB0AG8AcgBpAG4AZwAgA'
            - 'QAaQBzAGEAYgBsAGUAYgBlAGgAYQB2AGkAbwByAG0AbwBuAGkAdABvAHIAaQBuAGcAIA'
            - 'kAGkAcwBhAGIAbABlAGIAZQBoAGEAdgBpAG8AcgBtAG8AbgBpAHQAbwByAGkAbgBnACAA'
            - 'ZABpAHMAYQBiAGwAZQBiAGwAbwBjAGsAYQB0AGYAaQByAHMAdABzAGUAZQBuACAA'
            - 'QAaQBzAGEAYgBsAGUAYgBsAG8AYwBrAGEAdABmAGkAcgBzAHQAcwBlAGUAbgAgA'
            - 'kAGkAcwBhAGIAbABlAGIAbABvAGMAawBhAHQAZgBpAHIAcwB0AHMAZQBlAG4AIA'
            - 'RABpAHMAYQBiAGwAZQBDAGEAdABjAGgAdQBwAEYAdQBsAGwAUwBjAGEAbgA'
            - 'RABpAHMAYQBiAGwAZQBDAGEAdABjAGgAdQBwAFEAdQBpAGMAawBTAGMAYQBuAA'
            - 'RABpAHMAYQBiAGwAZQBBAHIAYwBoAGkAdgBlAFMAYwBhAG4AbgBpAG4AZwA'
    condition: all of selection_cli_* or 1 of selection_encoded_*
falsepositives:
    - Possible administrative activity
    - Other Cmdlets that may use the same parameters
level: high

Original YAML and metadata in JSON

False positives

• Possible administrative activity
• Other Cmdlets that may use the same parameters

Source references

• https://learn.microsoft.com/en-us/powershell/module/defender/set-mppreference?view=windowsserver2022-ps
• https://www.virustotal.com/gui/file/d609799091731d83d75ec5d1f030571af20c45efeeb94840b67ea09a3283ab65/behavior/C2AE
• https://www.virustotal.com/gui/search/content%253A%2522Set-MpPreference%2520-Disable%2522/files