CVE-2016-5392 in OpenShift Enterprise
Summary
by MITRE
The API server in Kubernetes, as used in Red Hat OpenShift Enterprise 3.2, in a multi tenant environment allows remote authenticated users with knowledge of other project names to obtain sensitive project and user information via vectors related to the watch-cache list.
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Analysis
by VulDB Data Team • 09/13/2022
The vulnerability identified as CVE-2016-5392 affects the Kubernetes API server implementation within Red Hat OpenShift Enterprise 3.2, specifically in multi-tenant environments where security isolation is paramount. This weakness stems from insufficient access controls and information disclosure mechanisms within the watch-cache list functionality, which is designed to optimize API server performance by maintaining cached views of cluster resources. The vulnerability represents a significant security gap that undermines the fundamental security model of container orchestration platforms where multiple tenants share the same infrastructure while maintaining strict isolation boundaries.
The technical flaw manifests through the improper handling of watch-cache list operations that allow authenticated users to access project and user information belonging to other tenants within the same cluster. When users possess knowledge of legitimate project names within the system, they can exploit this vulnerability to enumerate and retrieve sensitive metadata that should remain isolated between different project namespaces. This occurs because the watch-cache mechanism does not properly enforce authorization checks when serving list operations, allowing cross-tenant information leakage through the API server's caching layer that was intended to improve performance but inadvertently created a security weakness.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables attackers to perform reconnaissance activities that could lead to more sophisticated attacks. An authenticated user with knowledge of other project names can map the entire project landscape of an OpenShift cluster, identifying potential targets for further exploitation including users with elevated privileges, applications with sensitive data, or projects containing critical infrastructure components. This reconnaissance capability aligns with attack patterns documented in the attack technique matrix under the information gathering category, where adversaries first establish knowledge of the target environment before executing more targeted attacks. The vulnerability particularly impacts multi-tenant deployments where multiple organizations or teams share the same cluster infrastructure, making it a critical concern for cloud service providers and enterprise organizations utilizing container orchestration platforms.
Mitigation strategies for CVE-2016-5392 require immediate attention through patching mechanisms provided by Red Hat, as well as architectural considerations for cluster administrators. The most effective immediate solution involves applying the relevant security patches that address the watch-cache list authorization checks and ensure proper isolation between tenant projects. Additionally, cluster administrators should implement network segmentation controls to limit access to the API server, enforce strict role-based access controls through Kubernetes RBAC mechanisms, and regularly audit project and user access patterns to detect anomalous behavior. Organizations should also consider implementing additional monitoring solutions that can detect unusual API server activity patterns that might indicate exploitation attempts of this vulnerability, aligning with security best practices outlined in the CWE catalog under weakness category 284 for improper access control. The vulnerability serves as a reminder of the critical importance of proper authorization enforcement even in performance-optimized components of complex systems, highlighting the need for comprehensive security testing of all API server functionalities in multi-tenant environments.