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Description

The following analytic detects the creation of a new task with the highest execution privilege via Schtasks.exe. This tactic is often observed in AsyncRAT attacks, where the scheduled task is used for persistence and privilege escalation. AsyncRAT sets up a scheduled task with parameters '/rl' and 'highest', triggering this technique. It's a strong indicator of potential malware or adversaries seeking to establish persistence and escalate privileges through scheduled tasks. This is crucial for a Security Operations Center (SOC) as it can prevent unauthorized system access and potential data breaches.
The analytic works by monitoring logs for process name, parent process, and command-line executions. In the presence of the '*/rl ' and ' highest *' commands in a schtasks.exe process, an alert is triggered.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2023-01-26
  • Author: Teoderick Contreras, Splunk
  • ID: 2f15e1a4-0fc2-49dd-919e-cbbe60699218

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1053 Scheduled Task/Job Execution, Persistence, Privilege Escalation
T1053.005 Scheduled Task Execution, Persistence, Privilege Escalation
Kill Chain Phase
  • Installation
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


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| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime  from datamodel=Endpoint.Processes where Processes.process_name = "schtasks.exe" Processes.process = "*/rl *" Processes.process = "* highest *" by Processes.process_name Processes.parent_process_name Processes.parent_process Processes.process Processes.process_guid Processes.dest Processes.user 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_scheduled_task_with_highest_privileges_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_scheduled_task_with_highest_privileges_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • Processes.dest
  • Processes.user
  • Processes.parent_process_name
  • Processes.parent_process
  • Processes.original_file_name
  • Processes.process_name
  • Processes.process
  • Processes.process_id
  • Processes.parent_process_path
  • Processes.process_path
  • Processes.parent_process_id

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

False positives may arise from legitimate applications that create tasks to run as SYSTEM. Therefore, it's recommended to adjust filters based on parent process or modify the query to include world writable paths for restriction.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
64.0 80 80 a $process_name$ creating a schedule task $process$ with highest run level privilege in $dest$

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

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 | version: 1