Detection: Splunk protocol impersonation weak encryption selfsigned

Description

The following analytic identifies the use of Splunk's default self-signed certificates, which are flagged as insecure. It detects events from the splunkd log where the event message indicates that an X509 certificate should not be used. This activity is significant because using weak encryption and self-signed certificates can expose the system to man-in-the-middle attacks and other security vulnerabilities. If confirmed malicious, attackers could impersonate Splunk services, intercept sensitive data, and compromise the integrity of the Splunk environment.

Search

1`splunkd` certificate event_message="X509 certificate* should not be used*" 
2| stats count by host CN component log_level 
3| `splunk_protocol_impersonation_weak_encryption_selfsigned_filter`

Data Source

Name	Platform	Sourcetype	Source
Splunk	Splunk	'splunkd_ui_access'	'splunkd_ui_access.log'

Macros Used

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Implementation

Must upgrade to Splunk version 9 and Configure TLS in order to apply this search. Splunk SOAR customers can find a SOAR workbook that walks an analyst through the process of running these hunting searches in the references list of this detection. In order to use this workbook, a user will need to run a curl command to post the file to their SOAR instance such as "curl -u username:password https://soar.instance.name/rest/rest/workbook_template -d @splunk_psa_0622.json". A user should then create an empty container or case, attach the workbook, and begin working through the tasks.

Known False Positives

This searches finds self signed certificates issued by Splunk which are not recommended from Splunk version 9 forward.

Associated Analytic Story

• Splunk Vulnerabilities

Risk Based Analytics (RBA)

References

• https://www.splunk.com/en_us/product-security

• https://docs.splunk.com/Documentation/Splunk/9.0.0/Security/EnableTLSCertHostnameValidation

• https://www.github.com/splunk/security_content/blob/develop/workbooks/splunk_psa_0622.json

Detection Testing

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: GitHub | Version: 3