GitHub Repo

Detection: Excessive File Deletion In WinDefender Folder

Updated Date: 2026-05-13 ID: b5baa09a-7a05-11ec-8da4-acde48001122 Author: Teoderick Contreras, Splunk, Steven Dick Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects excessive file deletion events in the Windows Defender folder. It leverages Sysmon EventCodes 23 and 26 to identify processes deleting multiple files within this directory. This behavior is significant as it may indicate an attempt to corrupt or disable Windows Defender, a key security component. If confirmed malicious, this activity could allow an attacker to disable endpoint protection, facilitating further malicious actions without detection.

1`sysmon` EventCode IN ("23","26") TargetFilename = "*\\ProgramData\\Microsoft\\Windows Defender\\*" 
2| stats count min(_time) as firstTime, max(_time) as lastTime values(file_path) as file_path values(file_hash) as file_hash values(file_name) as file_name values(file_modify_time) as file_modify_time values(process_name) as process_name values(process_path) as process_path values(process_guid) as process_guid values(process_id) as process_id values(process_exec) as process_exec by action dest dvc signature signature_id user user_id vendor_product 
3| where count >=50 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `excessive_file_deletion_in_windefender_folder_filter`

Data Source

Name Platform Sourcetype Source
Sysmon EventID 26 Windows icon Windows 'XmlWinEventLog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Sysmon EventID 23 Windows icon Windows 'XmlWinEventLog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'

Macros Used

Name Value
sysmon (source=WinEventLog:Microsoft-Windows-Sysmon/Operational OR source=XmlWinEventLog:Microsoft-Windows-Sysmon/Operational OR source=Syslog:Linux-Sysmon/Operational)
excessive_file_deletion_in_windefender_folder_filter search *
excessive_file_deletion_in_windefender_folder_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
T1485 Data Destruction Impact
Actions on Objectives
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 search, you must ingest logs that include the process name, TargetFilename, and ProcessID executions from your endpoints. If you are utilizing Sysmon, ensure you have at least version 2.0 of the Sysmon TA installed.

Known False Positives

Windows Defender AV updates may trigger this alert. Please adjust the filter macros to mitigate false positives.

Associated Analytic Story

Finding

Title Entity Field Entity Type Risk Score
Excessive file deletion events were detected in the Windows Defender folder on $dest$ by $user$. Investigate further to determine if this activity is malicious. user user 50

Intermediate Findings

Message Entity Field Entity Type Risk Score
Excessive file deletion events were detected in the Windows Defender folder on $dest$ by $user$. Investigate further to determine if this activity is malicious. dest system 50

Threat Objects

Field Type
file_name file_name

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational XmlWinEventLog
Integration ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/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: 10