: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.

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Description

This search will return a table of processes in the a given window, remove process names which are in the allowed list and list out the top 30 rare processes discovered on different hosts.

  • Type: Anomaly
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2022-11-10
  • Author: Bhavin Patel, Splunk
  • ID: 44fddcb2-8d3b-454c-874e-7c6de5a4f7ac

Annotations

ATT&CK
Kill Chain Phase
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


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| 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 
| `filter_rare_process_allow_list` 
| sort count 
| head 30 
| rex field=user "(?<user_domain>.*)\\\\(?<user_name>.*)" 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `detect_rare_executables_filter`

Macros

The SPL above uses the following Macros:

:information_source: detect_rare_executables_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.dest
  • Processes.user
  • Processes.process_name

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.

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.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
25.0 50 50 tbd

: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: 3