GitHub Repo

Detection: Powershell Remove Windows Defender Directory

Updated Date: 2026-05-13 ID: adf47620-79fa-11ec-b248-acde48001122 Author: Teoderick Contreras, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects a suspicious PowerShell command attempting to delete the Windows Defender directory. It leverages PowerShell Script Block Logging to identify commands containing "rmdir" and targeting the Windows Defender path. This activity is significant as it may indicate an attempt to disable or corrupt Windows Defender, a key security component. If confirmed malicious, this action could allow an attacker to bypass endpoint protection, facilitating further malicious activities without detection.

1`powershell` EventCode=4104 ScriptBlockText = "*rmdir *" AND ScriptBlockText = "*\\Microsoft\\Windows Defender*" 
2| fillnull 
3| stats count min(_time) as firstTime max(_time) as lastTime by dest signature signature_id user_id vendor_product EventID Guid Opcode Name Path ProcessID ScriptBlockId ScriptBlockText 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `powershell_remove_windows_defender_directory_filter`

Data Source

Name Platform Sourcetype Source
Powershell Script Block Logging 4104 Windows icon Windows 'XmlWinEventLog' 'XmlWinEventLog:Microsoft-Windows-PowerShell/Operational'

Macros Used

Name Value
powershell (source=WinEventLog:Microsoft-Windows-PowerShell/Operational OR source="XmlWinEventLog:Microsoft-Windows-PowerShell/Operational" OR source=WinEventLog:PowerShellCore/Operational OR source="XmlWinEventLog:PowerShellCore/Operational")
powershell_remove_windows_defender_directory_filter search *
powershell_remove_windows_defender_directory_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1685 Disable or Modify Tools Defense Impairment
Exploitation
DE.CM
CIS 10

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Finding (Notable) Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Intermediate Finding (Risk Event) Yes
TTP detections generate a Finding (Notable) and may generate Intermediate Findings (Risk Events) for associated entities.

Implementation

To successfully implement this analytic, you will need to enable PowerShell Script Block Logging on some or all endpoints. Additional setup here https://help.splunk.com/en/security-offerings/splunk-user-behavior-analytics/get-data-in/5.4.1/add-other-data-to-splunk-uba/configure-powershell-logging-to-see-powershell-anomalies-in-splunk-uba.

Known False Positives

No false positives have been identified at this time.

Associated Analytic Story

Finding

Title Entity Field Entity Type Risk Score
suspicious powershell script $ScriptBlockText$ was executed on the $dest$ user_id user 50

Intermediate Findings

Message Entity Field Entity Type Risk Score
suspicious powershell script $ScriptBlockText$ was executed on the $dest$ dest system 50

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-PowerShell/Operational XmlWinEventLog
Integration ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-PowerShell/Operational XmlWinEventLog

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 16