Scheduled Task Deleted Or Created via CMD
Description
The following analytic detects the creation or deletion of scheduled tasks via schtasks.exe when invoked with create or delete flags, specifically focusing on those executions where the process includes additional parameters such as /tr, /sc, or /ru. The detection uses Endpoint Detection and Response (EDR) telemetry mapped to the Endpoint data model, and filters out events originating from trusted system paths like C:\Windows\System32 or C:\Program Files. It further narrows results to cases where schtasks.exe is launched by potentially suspicious parent processes such as cmd.exe, wscript.exe, or cscript.exe, and excludes service accounts. This behavior may indicate adversary efforts to gain persistence or evade detection by manipulating scheduled tasks using scripts or command shells. If confirmed malicious, such activity could lead to unauthorized code execution or the removal of monitoring mechanisms on endpoints.
Query · spl
| tstats `security_content_summariesonly`
count
min(_time) as firstTime
max(_time) as lastTime
FROM datamodel=Endpoint.Processes WHERE
Processes.parent_process_name="cmd.exe"
Processes.process_name="schtasks.exe"
Processes.process IN (
"*/create*",
"*-create*",
"*/delete*",
"*-delete*"
)
NOT Processes.process IN (
"* \"C:\\Program Files (x86)\\*",
"* \"C:\\Program Files\\*",
"* \"C:\\Windows\\System32\\*",
"* \"C:\\Windows\\SysWOW64\\*",
"* C:\\Program Files (x86)\\*",
"* C:\\Program Files\\*",
"* C:\\Windows\\System32\\*",
"* C:\\Windows\\SysWOW64\\*"
)
NOT Processes.user="*$"
BY Processes.action Processes.dest Processes.original_file_name
Processes.parent_process Processes.parent_process_exec
Processes.parent_process_guid Processes.parent_process_id
Processes.parent_process_name Processes.parent_process_path
Processes.process Processes.process_exec Processes.process_guid
Processes.process_hash Processes.process_id Processes.process_integrity_level
Processes.process_name Processes.process_path Processes.user
Processes.user_id Processes.vendor_product
| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `scheduled_task_deleted_or_created_via_cmd_filter`
Implementation guide
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
- While it is possible for legitimate scripts or administrators to trigger this behavior, filtering can be applied based on the parent process and application to reduce false positives. Analysts should reference the provided references to understand the context and threat landscape associated with this activity.
Analyst notes
Known false positives: While it is possible for legitimate scripts or administrators to trigger this behavior, filtering can be applied based on the parent process and application to reduce false positives. Analysts should reference the provided references to understand the context and threat landscape associated with this activity.