WARNING THIS IS A EXPERIMENTAL object

We have not been able to test, simulate, or build datasets for this object. Use at your own risk. This analytic is NOT supported.

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Description

The following hunting analytic leverages Event ID 4698, A scheduled task was created, to identify the creation of a Scheduled Task with a suspicious, high entropy, Task Name. To achieve this, this analytic also leverages the ut_shannon function from the URL ToolBox Splunk application. Red teams and adversaries alike may abuse the Task Scheduler to create and start a remote Scheduled Task and obtain remote code execution. To achieve this goal, tools like Impacket or Crapmapexec, typically create a Scheduled Task with a random task name on the victim host. This hunting analytic may help defenders identify Scheduled Tasks created as part of a lateral movement attack. The entropy threshold ut_shannon > 3 should be customized by users. The Command field can be used to determine if the task has malicious intent or not.

  • Type: Hunting
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2021-11-29
  • Author: Mauricio Velazco, Splunk
  • ID: 9d22a780-5165-11ec-ad4f-3e22fbd008af

Annotations

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
CIS20
CVE
1
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3
4
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6
 `wineventlog_security` EventCode=4698 
| xmlkv Message 
| lookup ut_shannon_lookup word as Task_Name 
| where ut_shannon > 3 
| table  _time, dest, Task_Name, ut_shannon, Command, Author, Enabled, Hidden 
| `randomly_generated_scheduled_task_name_filter`

Macros

The SPL above uses the following Macros:

Note that randomly_generated_scheduled_task_name_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required field

  • _time
  • dest
  • Task_Name
  • Description
  • Command

How To Implement

To successfully implement this search, you need to be ingesting Windows Security Event Logs with 4698 EventCode enabled. The Windows TA as well as the URL ToolBox application are also required.

Known False Positives

Legitimate applications may use random Scheduled Task names.

Associated Analytic story

RBA

Risk Score Impact Confidence Message
45.0 90 50 A windows scheduled task with a suspicious task name was created on $dest$

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