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Description

The following analytic utilizes Windows Security EventCode 4698, which indicates the creation of a scheduled task on a Windows system. The purpose of this query is to identify suspicious tasks that have been registered using either schtasks.exe or TaskService and involve executing a command from a user-writable file path.
When this analytic is triggered, it provides information such as the first and last registration time of the task, the command to be executed, the task name, author, and whether it is set as hidden or not. It is worth noting that schtasks.exe is commonly located in C:\Windows\system32 and C:\Windows\syswow64, and it loads the taskschd.dll DLL when launched. If this DLL is loaded by another process, it suggests that a scheduled task may be registered within that process's context in memory.
During the triage process, it is essential to identify the source of the scheduled task creation, whether it was initiated through schtasks.exe or TaskService. The analyst should review the task that was created, including the command to be executed. Additionally, any artifacts on disk related to the task should be captured and analyzed. It is also recommended to identify any parallel processes that occurred within the same timeframe to determine the source of the task creation.
By conducting this triage process, security analysts can gain insights into potentiallymalicious or suspicious scheduled tasks, helping them identify the source and assess the impact of the task. This analytic is valuable for a Security Operations Center (SOC) as it can detect unauthorized or suspicious activity that could indicate an attacker's attempt to establish persistence or execute unauthorized commands on the system.

  • Type: TTP

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

  • Last Updated: 2024-02-06
  • Author: Michael Haag, Splunk
  • ID: 5d9c6eee-988c-11eb-8253-acde48001122

Annotations

ATT&CK

ATT&CK

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


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`wineventlog_security` EventCode=4698 
| xmlkv Message 
| search Command IN ("*\\users\\public\\*", "*\\programdata\\*", "*\\temp\\*", "*\\Windows\\Tasks\\*", "*\\appdata\\*", "*\\perflogs\\*") 
| stats count min(_time) as firstTime max(_time) as lastTime by ComputerName, Task_Name, Command, Author, Enabled, Hidden 
|  rename ComputerName as dest 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `winevent_scheduled_task_created_within_public_path_filter`

Macros

The SPL above uses the following Macros:

:information_source: winevent_scheduled_task_created_within_public_path_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
  • 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 is also required.

Known False Positives

False positives are possible if legitimate applications are allowed to register tasks in public paths. Filter as needed based on paths that are used legitimately.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
70.0 70 100 A windows scheduled task was created (task name=$Task_Name$) on $dest$

: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: 2