Windows Registry Delete Task SD

name: Windows Registry Delete Task SD
id: ffeb7893-ff06-446f-815b-33ca73224e92
version: 10
date: '2026-03-10'
author: Michael Haag, Teoderick Contreras, Splunk
status: production
type: Anomaly
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 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.
data_source:
    - Sysmon EventID 12
search: |
    | tstats `security_content_summariesonly`
      count min(_time) as firstTime
            max(_time) as lastTime

    FROM datamodel=Endpoint.Registry where

    Registry.registry_path IN ("*\\Schedule\\TaskCache\\Tree\\*")
    Registry.user="SYSTEM"
    (
      Registry.registry_value_name="SD"
      OR
      Registry.registry_key_name="SD"
    )
    Registry.action=deleted

    by Registry.action Registry.dest Registry.process_guid
       Registry.process_id Registry.registry_hive
       Registry.registry_path Registry.registry_key_name
       Registry.registry_value_data Registry.registry_value_name
       Registry.registry_value_type Registry.status Registry.user
       Registry.vendor_product

    | `drop_dm_object_name(Registry)`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `windows_registry_delete_task_sd_filter`
how_to_implement: 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.
references:
    - https://www.microsoft.com/security/blog/2022/04/12/tarrask-malware-uses-scheduled-tasks-for-defense-evasion/
    - https://gist.github.com/MHaggis/5f7fd6745915166fc6da863d685e2728
    - https://gist.github.com/MHaggis/b246e2fae6213e762a6e694cabaf0c17
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") starthoursago=168  | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
rba:
    message: A scheduled task security descriptor $registry_path$ was deleted from the registry on $dest$.
    risk_objects:
        - field: dest
          type: system
          score: 20
    threat_objects:
        - field: registry_path
          type: registry_path
tags:
    analytic_story:
        - Windows Registry Abuse
        - Windows Persistence Techniques
        - Scheduled Tasks
    asset_type: Endpoint
    mitre_attack_id:
        - T1053.005
        - T1562
    product:
        - Splunk Enterprise
        - Splunk Enterprise Security
        - Splunk Cloud
    security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1053.005/taskschedule/sd_delete_windows-sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog