Detection: Splunk Protocol Impersonation Weak Encryption Configuration

Description

The following analytic identifies weak encryption configurations in Splunk related to TLS validation within the httplib and urllib Python libraries. It uses REST API calls to check specific configuration settings on the search head and its peers, ensuring compliance with security advisories. This activity is significant for a SOC as weak encryption can be exploited for protocol impersonation attacks, leading to unauthorized access. If confirmed malicious, attackers could intercept and manipulate data, compromising the integrity and confidentiality of the Splunk environment.

Search

 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="PythonSslClientConfig" 
 6| table splunk_server sslVerifyServerCert sslVerifyServerName] 
 7| join splunk_server [
 8| rest /servicesNS/nobody/search/configs/conf-web/settings 
 9|  table splunk_server serverCert sslVersions] 
10| rename sslVerifyServerCert as "Server.conf:PythonSSLClientConfig:sslVerifyServerCert", sslVerifyServerName as "Server.conf:PythonSSLClientConfig:sslVerifyServerName", serverCert as "Web.conf:Settings:serverCert", sslVersions as "Web.conf:Settings:sslVersions" 
11| `splunk_protocol_impersonation_weak_encryption_configuration_filter`

Data Source

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

Macros Used

| splunk_protocol_impersonation_weak_encryption_configuration_filter | search * |

Annotations

Default Configuration

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

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). 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

While all of the settings on each device returned by this search may appear to be hardened, you will still need to verify the value of PYTHONHTTPSVERIFY in $SPLUNK_HOME/etc/splunk-launch.conf on each device in order to harden the python configuration.

Associated Analytic Story

• Splunk Vulnerabilities

Risk Based Analytics (RBA)

References

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

• https://www.splunk.com/en_us/product-security/announcements/svd-2022-0601.html

• 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