:warning: THIS IS A EXPERIMENTAL DETECTION

This detection has been marked experimental by the Splunk Threat Research team. This means we have not been able to test, simulate, or build datasets for this detection. Use at your own risk. This analytic is NOT supported.

Try in Splunk Security Cloud

Description

Command lines that are extremely long may be indicative of malicious activity on your hosts.

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

  • Last Updated: 2020-12-08
  • Author: David Dorsey, Splunk
  • ID: c77162d3-f93c-45cc-80c8-22f6a4264e7f

Annotations

ATT&CK
Kill Chain Phase
  • Actions on Objectives
NIST
  • PR.PT
  • DE.CM
CIS20
  • CIS 8
CVE
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| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes by Processes.user Processes.dest Processes.process_name Processes.process 
| `drop_dm_object_name("Processes")` 
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
|  eval processlen=len(process) 
| eventstats stdev(processlen) as stdev, avg(processlen) as avg by dest 
| stats max(processlen) as maxlen, values(stdev) as stdevperhost, values(avg) as avgperhost by dest, user, process_name, process 
| `unusually_long_command_line_filter` 
|eval threshold = 3 
| where maxlen > ((threshold*stdevperhost) + avgperhost)

Macros

The SPL above uses the following Macros:

:information_source: unusually_long_command_line_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.dest
  • Processes.process_name
  • Processes.process

How To Implement

You must be ingesting endpoint data that tracks process activity, including parent-child relationships, from your endpoints to populate the Endpoint data model in the Processes node. The command-line arguments are mapped to the process field in the Endpoint data model.

Known False Positives

Some legitimate applications start with long command lines.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
42.0 70 60 Unusually long command line $Processes.process_name$ 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: 5