ID | Technique | Tactic |
---|---|---|
T1053.005 | Scheduled Task | Execution |
T1562 | Impair Defenses | Persistence |
Detection: Windows Registry Delete Task SD
Description
The following analytic detects a process attempting to delete a scheduled task's Security Descriptor (SD) from the registry path of that task. It leverages the Endpoint.Registry data model to identify registry actions performed by the SYSTEM user, specifically targeting deletions or modifications of the SD value. This activity is significant as it may indicate an attempt to remove evidence of a scheduled task for defense evasion. If confirmed malicious, it suggests an attacker with privileged access trying to hide their tracks, potentially compromising system integrity and security. Immediate investigation is required.
Search
1
2| tstats `security_content_summariesonly` count from datamodel=Endpoint.Registry where Registry.registry_path IN ("*\\Schedule\\TaskCache\\Tree\\*") Registry.user="SYSTEM" Registry.registry_value_name="SD" (Registry.action=Deleted OR Registry.action=modified) by _time Registry.dest Registry.process_guid Registry.user Registry.registry_path Registry.registry_value_name Registry.registry_key_name Registry.registry_value_data Registry.status Registry.action
3| `drop_dm_object_name(Registry)`
4| `security_content_ctime(firstTime)`
5| `security_content_ctime(lastTime)`
6| `windows_registry_delete_task_sd_filter`
Data Source
Name | Platform | Sourcetype | Source | Supported App |
---|---|---|---|---|
Sysmon EventID 12 | Windows | 'xmlwineventlog' |
'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational' |
N/A |
Macros Used
Name | Value |
---|---|
security_content_ctime | convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$) |
windows_registry_delete_task_sd_filter | search * |
windows_registry_delete_task_sd_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
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 Risk Event | True |
Implementation
To successfully implement this search you need to be ingesting information on process that include the name of the process responsible for the changes from your endpoints into the Endpoint
datamodel in the Registry
node. In addition, confirm the latest CIM App 4.20 or higher is installed and the latest TA for the endpoint product.
Known False Positives
False positives should be limited as the activity is not common to delete ONLY the SD from the registry. Filter as needed. Update the analytic Modified or Deleted values based on product that is in the datamodel.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
A scheduled task security descriptor was deleted from the registry on $dest$. | 49 | 70 | 70 |
References
-
https://gist.github.com/MHaggis/5f7fd6745915166fc6da863d685e2728
-
https://gist.github.com/MHaggis/b246e2fae6213e762a6e694cabaf0c17
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: 2