Detection: Powershell Remove Windows Defender Directory

Updated Date: 2026-06-29 ID: adf47620-79fa-11ec-b248-acde48001122 Author: Teoderick Contreras, Splunk Type: Anomaly 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.

Search

 1`powershell`
 2EventCode=4104
 3ScriptBlockText = "*rmdir *"
 4ScriptBlockText = "*\\Microsoft\\Windows Defender*"
 5
 6| fillnull
 7
 8| stats count min(_time) as firstTime
 9              max(_time) as lastTime
10  by dest signature signature_id user_id
11     vendor_product EventID Guid Opcode
12     Name Path ProcessID
13     ScriptBlockId ScriptBlockText
14
15| `security_content_ctime(firstTime)`
16
17| `security_content_ctime(lastTime)`
18
19| `powershell_remove_windows_defender_directory_filter`

Data Source

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

Macros Used

Name	Value
security_content_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
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.AE

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)	No
Creates Intermediate Finding (Risk Event)	Yes

Anomaly detections generate Intermediate Findings (Risk Events). They do not generate a Finding (Notable) directly.

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

Intermediate Findings

Message	Entity Field	Entity Type	Risk Score
A suspicious powershell script with the ScriptBlockId [$ScriptBlockId$] containing rmdir commands to potentially delete the Windows Defender directory was executed on host $dest$ by user $user_id$	dest	system	20
A suspicious powershell script with the ScriptBlockId [$ScriptBlockId$] containing rmdir commands to potentially delete the Windows Defender directory was executed on host $dest$ by user $user_id$	user_id	user	20

References

https://www.microsoft.com/security/blog/2022/01/15/destructive-malware-targeting-ukrainian-organizations/

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: 17