Detection: Scheduled Task Creation on Remote Endpoint using At

Description

The following analytic detects the creation of scheduled tasks on remote Windows endpoints using the at.exe command. This detection leverages Endpoint Detection and Response (EDR) telemetry, focusing on process creation events involving at.exe with remote command-line arguments. Identifying this activity is significant for a SOC as it may indicate lateral movement or remote code execution attempts by an attacker. If confirmed malicious, this activity could lead to unauthorized access, persistence, or execution of malicious code, potentially resulting in data theft or further compromise of the network.

Search

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where (Processes.process_name=at.exe OR Processes.original_file_name=at.exe) (Processes.process=*\\\\*) by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id 
3| `drop_dm_object_name(Processes)` 
4| `security_content_ctime(firstTime)`
5| `security_content_ctime(lastTime)` 
6| `scheduled_task_creation_on_remote_endpoint_using_at_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	N/A	'crowdstrike:events:sensor'	'crowdstrike'
Sysmon EventID 1	Windows	'xmlwineventlog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Windows Event Log Security 4688	Windows	'xmlwineventlog'	'XmlWinEventLog:Security'

Macros Used

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Implementation

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

Administrators may create scheduled tasks on remote systems, but this activity is usually limited to a small set of hosts or users.

Associated Analytic Story

• Active Directory Lateral Movement

• Living Off The Land

• Scheduled Tasks

Risk Based Analytics (RBA)

References

• https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/at

• https://docs.microsoft.com/en-us/windows/win32/cimwin32prov/win32-scheduledjob?redirectedfrom=MSDN

Detection Testing

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: 4