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Description

The following analytic detects the creation of scheduled tasks in Windows that use the rundll32 command. It leverages Windows Security EventCode 4698, which logs the creation of scheduled tasks, and filters for tasks executed via rundll32. This activity is significant as it is a common technique used by malware, such as TrickBot, to persist in an environment or deliver additional payloads. If confirmed malicious, this could lead to data theft, ransomware deployment, or other damaging outcomes. Immediate investigation and mitigation are crucial to prevent further compromise.

  • Type: TTP

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

  • Last Updated: 2024-05-15
  • Author: Teoderick Contreras, Splunk
  • ID: 75b00fd8-a0ff-11eb-8b31-acde48001122

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
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 ("*rundll32*") 
| stats count min(_time) as firstTime max(_time) as lastTime by dest, Task_Name, Command, Author, Enabled, Hidden, Arguments 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `schedule_task_with_rundll32_command_trigger_filter`

Macros

The SPL above uses the following Macros:

:information_source: schedule_task_with_rundll32_command_trigger_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
  • Command
  • Author
  • Enabled
  • Hidden
  • Arguments

How To Implement

To successfully implement this search, you need to be ingesting logs with the task schedule (Exa. Security Log EventCode 4698) endpoints. Tune and filter known instances of Task schedule used in your environment.

Known False Positives

unknown

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
70.0 70 100 A schedule task process commandline rundll32 arguments $Arguments$ in host $dest$

: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