Splunk protocol impersonation weak encryption selfsigned

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Description

On June 14th 2022, Splunk released vulnerability advisory addresing Python TLS validation which was not set before Splunk version 9. This search displays events showing WARNING of using Splunk issued default selfsigned certificates.

• Type: Hunting

• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

• Last Updated: 2022-05-26
• Author: Rod Soto, Splunk
• ID: c76c7a2e-df49-414a-bb36-dce2683770de

Annotations

ATT&CK

ATT&CK

ID	Technique	Tactic
T1588.004	Digital Certificates	Resource Development

Kill Chain Phase

• Weaponization

NIST

• DE.AE

CIS20

• CIS 10

CVE

ID	Summary	CVSS
CVE-2022-32152	Splunk Enterprise peers in Splunk Enterprise versions before 9.0 and Splunk Cloud Platform versions before 8.2.2203 did not validate the TLS certificates during Splunk-to-Splunk communications by default. Splunk peer communications configured properly with valid certificates were not vulnerable. However, an attacker with administrator credentials could add a peer without a valid certificate and connections from misconfigured nodes without valid certificates did not fail by default. For Splunk Enterprise, update to Splunk Enterprise version 9.0 and Configure TLS host name validation for Splunk-to-Splunk communications (https://docs.splunk.com/Documentation/Splunk/9.0.0/Security/EnableTLSCertHostnameValidation) to enable the remediation.	6.5

Search

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

Macros

The SPL above uses the following Macros:

• splunkd

splunk_protocol_impersonation_weak_encryption_selfsigned_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.

• host
• CN
• event_message

How To Implement

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

RBA

Risk Score	Impact	Confidence	Message
40.0	50	80	Splunk default issued certificate at $host$

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

• 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

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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