splunk-security_content/docs/_posts/2020-03-16-detect_rare_executables.md

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

title	excerpt	categories	last_modified_at	toc	toc_label	tags
Detect Rare Executables		Endpoint	2020-03-16	true		Splunk Enterprise Splunk Enterprise Security Splunk Cloud Endpoint

⚠️ 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

This search will return a table of rare processes, the names of the systems running them, and the users who initiated each process.

• Type: Anomaly
• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel: Endpoint
• Last Updated: 2020-03-16
• Author: Bhavin Patel, Splunk
• ID: 44fddcb2-8d3b-454c-874e-7c6de5a4f7ac

Search

| tstats `security_content_summariesonly` count values(Processes.dest) as dest values(Processes.user) as user min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes by Processes.process_name  
| rename Processes.process_name as process 
| rex field=user "(?<user_domain>.*)\\\\(?<user_name>.*)" 
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| search [
| tstats count from datamodel=Endpoint.Processes by Processes.process_name 
| rare Processes.process_name limit=30 
| rename Processes.process_name as process
| `filter_rare_process_allow_list`
| table process ] 
| `detect_rare_executables_filter` 

Associated Analytic Story

• Emotet Malware DHS Report TA18-201A
• Unusual Processes
• Cloud Federated Credential Abuse

How To Implement

To successfully implement this search, you must be ingesting data that records process activity from your hosts and populating the endpoint data model with the resultant dataset. The macro filter_rare_process_allow_list searches two lookup files for allowed processes. These consist of rare_process_allow_list_default.csv and rare_process_allow_list_local.csv. To add your own processes to the allow list, add them to rare_process_allow_list_local.csv. If you wish to remove an entry from the default lookup file, you will have to modify the macro itself to set the allow_list value for that process to false. You can modify the limit parameter and search scheduling to better suit your environment.

Required field

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

Kill Chain Phase

• Installation
• Command and Control
• Actions on Objectives

Known False Positives

Some legitimate processes may be only rarely executed in your environment. As these are identified, update rare_process_allow_list_local.csv to filter them out of your search results.

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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