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

title, excerpt, categories, last_modified_at, toc, toc_label, tags

title	excerpt	categories	last_modified_at	toc	toc_label	tags
Single Letter Process On Endpoint	User Execution, Malicious File	Endpoint	2020-12-08	true		User Execution Execution Malicious File Execution Splunk Enterprise Splunk Enterprise Security Splunk Cloud Endpoint

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Description

This search looks for process names that consist only of a single letter.

• Type: TTP
• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel: Endpoint
• Last Updated: 2020-12-08
• Author: David Dorsey, Splunk
• ID: a4214f0b-e01c-41bc-8cc4-d2b71e3056b4

ATT&CK

ID	Technique	Tactic
T1204	User Execution	Execution

| T1204.002 | Malicious File | Execution |

Search

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes by Processes.dest, Processes.user, Processes.process, Processes.process_name 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(lastTime)` 
| `security_content_ctime(firstTime)` 
| eval process_name_length = len(process_name), endExe = if(substr(process_name, -4) == ".exe", 1, 0) 
| search process_name_length=5 AND endExe=1 
| table count, firstTime, lastTime, dest, user, process, process_name 
| `single_letter_process_on_endpoint_filter`

Associated Analytic Story

• DHS Report TA18-074A

How To Implement

You must be ingesting data that records process activity from your hosts to populate the Endpoint data model in the Processes node. You must also be ingesting logs with both the process name and command line from your endpoints. The command-line arguments are mapped to the "process" field in the Endpoint data model.

Required field

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

Kill Chain Phase

• Actions on Objectives

Known False Positives

Single-letter executables are not always malicious. Investigate this activity with your normal incident-response process.

RBA

Risk Score	Impact	Confidence	Message
63.0	70	90	A suspicious process process_name with single letter in host 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/T1204.002/single_letter_exe/windows-sysmon.log

source | version: 3