Disabling Windows Defender Security Settings via PowerShell

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Disabling Windows Defender Security Settings via PowerShell

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Identifies use of the Set-MpPreference PowerShell command to disable or weaken certain Windows Defender settings.

Rule type: eql

Rule indices:

winlogbeat-*
logs-endpoint.events.*
logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

https://docs.microsoft.com/en-us/powershell/module/defender/set-mppreference?view=windowsserver2019-ps

Tags:

Elastic
Host
Windows
Threat Detection
Defense Evasion

Version: 2 (version history)

Added (Elastic Stack release): 7.14.0

Last modified (Elastic Stack release): 7.16.0

Rule authors: Elastic

Rule license: Elastic License v2

Potential false positives

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Planned Windows Defender configuration changes.

Rule query

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process where event.type == "start" and (process.name :
("powershell.exe", "pwsh.exe", "powershell_ise.exe") or
process.pe.original_file_name in ("powershell.exe", "pwsh.dll",
"powershell_ise.exe")) and process.args : "Set-MpPreference" and
process.args : ("-Disable*", "Disabled", "NeverSend", "-Exclusion*")

Threat mapping

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Framework: MITRE ATT&CK^TM

Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
Technique:
- Name: Impair Defenses
- ID: T1562
- Reference URL: https://attack.mitre.org/techniques/T1562/

Rule version history

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Version 2 (7.16.0 release)

Updated query, changed from:

process where event.type == "start" and (process.name :
("powershell.exe", "pwsh.exe") or process.pe.original_file_name ==
"PowerShell.EXE") and process.args : "Set-MpPreference" and
process.args : ("-Disable*", "Disabled", "NeverSend", "-Exclusion*")

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