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Description

This analytic is to detect a suspicious commandline to disable existing schedule task. This technique is used by adversaries or commodity malware like IcedID to disable security application (AV products) in the targetted host to evade detections. This TTP is a good pivot to check further why and what other process run before and after this detection. check which process execute the commandline and what task is disabled. parent child process is quite valuable in this scenario too.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2021-10-18
  • Author: Teoderick Contreras, Splunk
  • ID: db596056-3019-11ec-a9ff-acde48001122

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1562.001 Disable or Modify Tools Defense Evasion
T1562 Impair Defenses Defense Evasion
Kill Chain Phase
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 10
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=*/change*  Processes.process=*/disable* by Processes.user Processes.process_name Processes.process Processes.parent_process_name Processes.parent_process Processes.dest 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `disable_schedule_task_filter`

Macros

The SPL above uses the following Macros:

:information_source: disable_schedule_task_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.user
  • Processes.process_name
  • Processes.parent_process_name
  • Processes.dest

How To Implement

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

admin may disable problematic schedule task

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
56.0 70 80 schtask process with commandline $process$ to disable schedule task 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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