Detection: Short Lived Scheduled Task

Updated Date: 2024-12-10 ID: 6fa31414-546e-11ec-adfa-acde48001122 Author: Mauricio Velazco, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the creation and deletion of scheduled tasks within a short time frame (less than 30 seconds) using Windows Security EventCodes 4698 and 4699. This behavior is identified by analyzing Windows Security Event Logs and leveraging the Windows TA for parsing. Such activity is significant as it may indicate lateral movement or remote code execution attempts by adversaries. If confirmed malicious, this could lead to unauthorized access, data exfiltration, or execution of malicious payloads, necessitating prompt investigation and response by security analysts.

1`wineventlog_security` EventCode=4698 OR EventCode=4699 
2| xmlkv Message 
3| transaction Task_Name  startswith=(EventCode=4698) endswith=(EventCode=4699) 
4| eval short_lived=case((duration<30),"TRUE") 
5| search  short_lived = TRUE 
6| rename ComputerName as dest
7| table _time, dest, Account_Name, Command, Task_Name, short_lived 
8| `short_lived_scheduled_task_filter`

Data Source

Name Platform Sourcetype Source
Windows Event Log Security 4698 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Security'
Windows Event Log Security 4699 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Security'

Macros Used

Name Value
wineventlog_security eventtype="wineventlog_security" OR Channel="security" OR source="XmlWinEventLog:Security" OR source="WinEventLog:Security"
short_lived_scheduled_task_filter search *
short_lived_scheduled_task_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1053.005 Scheduled Task Execution
Exploitation
Installation
DE.CM
CIS 10

Default Configuration

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

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Risk Event True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

To successfully implement this search, you need to be ingesting Windows Security Event Logs with 4698 EventCode enabled. The Windows TA is also required.

Known False Positives

Although uncommon, legitimate applications may create and delete a Scheduled Task within 30 seconds. Filter as needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

A windows scheduled task was created and deleted in 30 seconds on $dest$

Risk Object Risk Object Type Risk Score Threat Objects
dest system 81 No Threat Objects

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset WinEventLog:Security WinEventLog
Integration ✅ Passing Dataset WinEventLog:Security WinEventLog

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: 6