Name:Windows Registry Delete Task SD id:ffeb7893-ff06-446f-815b-33ca73224e92 version:4 date:2024-11-14 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 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. Data_source:
-Sysmon EventID 12
-Sysmon EventID 13
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" (Registry.action=Deleted OR Registry.action=modified) by 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 | `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. Filter as needed. Update the analytic Modified or Deleted values based on product that is in the datamodel. 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:'$info_max_time$' tags: analytic_story: - 'Windows Registry Abuse' - 'Windows Persistence Techniques' - 'Scheduled Tasks' asset_type:Endpoint confidence:70 impact:70 message:A scheduled task security descriptor was deleted from the registry on $dest$. mitre_attack_id: - 'T1053.005' - 'T1562' observable: name:'dest' type:'Endpoint' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'Registry.registry_path' - 'Registry.registry_key_name' - 'Registry.registry_value_name' - 'Registry.dest' - 'Processes.process_id' - 'Processes.process_name' - 'Processes.process' - 'Processes.dest' - 'Processes.process_guid' risk_score:49 security_domain:endpoint
