Kube State Metrics Exposure Scanner

Kube State Metrics is a simple service that is used by developers and system administrators within Kubernetes environments. It provides metrics about the state of the objects managed by a Kubernetes cluster such as pods, nodes, and deployments. The service is intended to be used along with a monitoring system to ensure transparency and maintain operational efficiency. By serving Kubernetes state as metrics, Kube State Metrics allows for careful monitoring of cluster health. Additionally, Kube State Metrics is often used in conjunction with Prometheus to visualize and aggregate data in scalable environments. It's commonly employed in environments where maintaining Kubernetes clusters at scale is of paramount importance.

Exposure of Kube State Metrics represents a security misconfiguration which can lead to unintentional data leakage. This vulnerability occurs when the metrics are accessible publicly without proper access controls. Any unauthorized party can potentially intercept communications and gather information about the cluster. It increases the risk by exposing the state and status of Kubernetes objects, which could provide insights on operational blueprints attackers might exploit. This misconfiguration might not directly authorize changes but provides enough information for reconnaissance activities. It illustrates a common pitfall in Kubernetes security where observability tools assume default openness that should be mitigated. Enabling strict access controls and frequently auditing exposure settings can mitigate such vulnerabilities.

Technical details on this vulnerability involve the endpoint exposing metric data to unauthorized users. Specific paths that often get publicly exposed include the "/metrics" endpoint of Kube State Metrics. It is accessible through HTTP requests that, if not properly secured, display a wealth of information, such as the status of goroutine collections which shows the number of simultaneous running threads or processes. Additionally, the template identifies the use of key strings in the response, such as `kube-state-metrics` and `go_goroutines`, confirming exposure. Successful exploitation of the vulnerability allows an attacker to consume such responses to inform more significant exploits. Therefore, implementing request limits and stringent HTTP status code checks may act as preventive measures.

The possible effects of exposing Kube State Metrics include unauthorized information disclosure which could lead to a security breach. Publicly available Kubernetes metrics provide insights into the application state and structure, potentially revealing critical operational insights. This can aid attackers in mapping out the structure and functionality of the cluster, enabling them to launch more targeted and disruptive attacks. Furthermore, such insight into system operations may lead to increased load or denial-of-service if exploited in volume. If attackers understand how pods and nodes operate, they can leverage other vulnerabilities effectively. Thus, exposure exacerbates existing misconfigurations or vulnerabilities within the cluster, amplifying potential damage.

REFERENCES

• https://kubernetes.io/blog
• https://kubernetes.io/docs/concepts/cluster-administration/monitoring/