Appending __raw/services/server/info/server-info?output_mode=json to a query in Splunk 7.0.1 can lead to sensitive information disclosure by exposing system details that should ideally remain restricted.
This endpoint provides an extensive JSON output containing critical metadata about the Splunk instance, including licensing details, system configurations, and version information.
How does Splunk sensitive information disclosure happen?
Splunk’s REST API allows users to retrieve various system details programmatically. While this is useful for legitimate administrative tasks, it can be exploited if access controls are not properly enforced. When an attacker or unauthorized user appends:
https://<splunk-instance>/en-US/__raw/services/server/info/server-info?output_mode=json
to a Splunk search query, they can retrieve detailed system-level information, including:
Splunk server version – useful for identifying known vulnerabilities.
Host details – Information about the underlying operating system and architecture.
Licensing key information – In certain cases, partial or full license keys may be exposed, which could be misused for unauthorized installations or resale.
Deployment metadata – Helps attackers map out the environment for further exploitation.
How can you prevent Splunk information disclosure?
Restrict API access – Ensure that only authorized users or roles can access sensitive REST API endpoints.
Mask sensitive data – Use Splunk’s built-in masking features to prevent sensitive information from being displayed in logs.
Upgrade Splunk – Running an outdated version (like 7.0.1) increases the risk of exposure due to unpatched vulnerabilities.
Audit API usage – Regularly monitor API access logs to detect unusual requests targeting sensitive endpoints.
Implement role-based access controls (RBAC) – Limit permissions so that only necessary users can access administrative endpoints.
Wrapping up
While Splunk is a robust and essential tool for log management, improper configurations can lead to unintended data leaks. Securing access to sensitive endpoints like /server-info is crucial to prevent unauthorized disclosures and potential security risks.
Ensuring that access controls are strictly enforced, and API endpoints are monitored will help protect against such threats.
