splunk-security_content/docs/_posts/2020-12-08-unusually_long_command_line.md

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title	excerpt	categories	last_modified_at	toc	toc_label	tags
Unusually Long Command Line		Endpoint	2020-12-08	true		Splunk Enterprise Splunk Enterprise Security Splunk Cloud

⚠️ WARNING THIS IS A EXPERIMENTAL DETECTION

We have not been able to test, simulate, or build datasets for this detection. Use at your own risk. This analytic is NOT supported.

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

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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)

Associated Analytic Story

• Suspicious Command-Line Executions
• Unusual Processes
• Possible Backdoor Activity Associated With MUDCARP Espionage Campaigns
• Ransomware

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.

Required field

• _time
• Processes.user
• Processes.dest
• Processes.process_name
• Processes.process

Kill Chain Phase

• Actions on Objectives

Known False Positives

Some legitimate applications start with long command lines.

RBA

Risk Score	Impact	Confidence	Message
42.0	70	60	Unusually long command line Processes.process_name on dest

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

• https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1036.003/atomic_red_team/windows-sysmon.log

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