Detection: Splunk Digital Certificates Infrastructure Version

Description

The following analytic identifies improper TLS validation configuration on Splunk search heads and peers post version 9. It leverages REST API calls to retrieve server information and SSL configuration settings, checking fields like sslVerifyServerCert and sslVerifyServerName. This activity is significant for a SOC as improper TLS settings can expose the infrastructure to man-in-the-middle attacks and data breaches. If confirmed malicious, attackers could intercept or manipulate data, compromising the integrity and confidentiality of communications within the Splunk environment.

1
2| rest /services/server/info 
3| table splunk_server version server_roles 
4| join splunk_server [
5| rest /servicesNS/nobody/search/configs/conf-server/ search="sslConfig"
6| table splunk_server sslVerifyServerCert sslVerifyServerName serverCert] 
7| fillnull value="Not Set" 
8| rename sslVerifyServerCert as "Server.conf:SslConfig:sslVerifyServerCert", sslVerifyServerName as "Server.conf:SslConfig:sslVerifyServerName", serverCert as "Server.conf:SslConfig:serverCert" 
9| `splunk_digital_certificates_infrastructure_version_filter`

Data Source

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

Macros Used

Name Value

| splunk_digital_certificates_infrastructure_version_filter | search * |

splunk_digital_certificates_infrastructure_version_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
T1587.003 Digital Certificates Resource Development
KillChainPhase.WEAPONIZATION
NistCategory.DE_AE
Cis18Value.CIS_10
APT29
PROMETHIUM

Default Configuration

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

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Risk Event False
This configuration file applies to all detections of type hunting.

Implementation

The user running this search is required to have a permission allowing them to dispatch REST requests to indexers (the dispatch_rest_to_indexers capability) in some architectures. 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

No known at this time.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
$splunk_server$ may not be properly validating TLS Certificates 50 50 100
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation Passing N/A N/A N/A
Unit Passing Dataset audittrail audittrail
Integration ✅ Passing Dataset audittrail audittrail

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