GitHub Repo

Detection: Splunk protocol impersonation weak encryption selfsigned

REMOVED DETECTION

This detection has been removed from the Splunk Threat Research content library and is no longer maintained or supported.

Reason: Detection is deprecated as the associated CVEs have been patched in the latest Splunk release.

Removed in version: 5.6.0

If you have any questions or concerns, please reach out to us at research@splunk.com.

Updated Date: 2026-05-14 ID: c76c7a2e-df49-414a-bb36-dce2683770de Author: Rod Soto, Splunk Type: Hunting Product: Splunk Enterprise Security

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.

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 icon Splunk 'splunkd_ui_access' 'splunkd_ui_access.log'

Macros Used

Name Value
splunkd index=_internal sourcetype=splunkd
splunk_protocol_impersonation_weak_encryption_selfsigned_filter ``
splunk_protocol_impersonation_weak_encryption_selfsigned_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1588.004 Digital Certificates Resource Development

CVE

Default Configuration

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

Setting Value
Disabled true
Cron Schedule N/A
Earliest Time N/A
Latest Time N/A
Schedule Window N/A
Creates Finding (Notable) No
Creates Intermediate Finding (Risk Event) No
Hunting detections do not generate a Finding (Notable) or Intermediate Findings (Risk Events).

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

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation Not Applicable N/A N/A N/A
Unit Not Applicable N/A N/A N/A

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: 6