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Description

The following analytic identifies Schtasks.exe creating a new task with highest privilege execution. This techniques was seen in asyncrat where it uses the scheduled task as part of it persistence and privilege escalation. AsyncRAT will setup a scheduled task with parameter '/rl' and 'highest' to trigger this technique. This TTP detection can be a good indicator of malware or adversaries trying to gain persistence and privilege escalation through scheduled task. We recommend to always check and monitoring this type of events even filtering is needed.

  • 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
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 3
  • CIS 5
  • CIS 16
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

To successfully implement this search, you need to be ingesting logs with the process name, parent process, and command-line executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA. Tune and filter known instances of wermgr.exe may be used.

Known False Positives

False positives will be limited to legitimate applications creating a task to run as SYSTEM. Filter as needed based on parent process, or modify the query to have world writeable paths to restrict it.

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

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