The following analytic identifies when the Task Scheduler service "svchost.exe -k netsvcs -p -s Schedule" is the parent process to common command line, scripting, or shell execution binaries. Attackers often abuse the task scheduler service with these binaries as an execution and persistence mechanism in order to blend in with normal Windows operations. This TTP is also commonly seen for legitimate purposes such as business scripts or application updates.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2023-06-13
- Author: Steven Dick
- ID: d8120352-3b62-4e3c-8cb6-7b47584dd5e8
Kill Chain Phase
- CIS 10
1 2 3 4 5 6 | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.parent_process="*\\system32\\svchost.exe*" AND Processes.parent_process="*-k*" AND Processes.parent_process= "*netsvcs*" AND Processes.parent_process="*-p*" AND Processes.parent_process="*-s*" AND Processes.parent_process="*Schedule*" Processes.process_name IN("powershell.exe", "wscript.exe", "cscript.exe", "cmd.exe", "sh.exe", "ksh.exe", "zsh.exe", "bash.exe", "scrcons.exe","pwsh.exe") by Processes.dest Processes.user Processes.parent_process Processes.process_name Processes.process Processes.process_id Processes.parent_process_id Processes.parent_process_name | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_scheduled_task_service_spawned_shell_filter`
The SPL above uses the following Macros:
windows_scheduled_task_service_spawned_shell_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
How To Implement
The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the
Processes node of the
Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.
Known False Positives
Unknown, possible custom scripting.
Associated Analytic Story
|20.0||80||25||A windows scheduled task spawned the shell application $process_name$ on $dest$.|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
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