C-0286 - Client certificate authentication should not be used for users

Prerequisites

Run Kubescape with host sensor (see here)

Framework

cis-v1.10.0

Severity

Medium

Description of the the issue

With any authentication mechanism the ability to revoke credentials if they are compromised or no longer required, is a key control. Kubernetes client certificate authentication does not allow for this due to a lack of support for certificate revocation.

Related resources

What does this control test

Kubernetes provides the option to use client certificates for user authentication. However as there is no way to revoke these certificates when a user leaves an organization or loses their credential, they are not suitable for this purpose.

It is not possible to fully disable client certificate use within a cluster as it is used for component to component authentication.

How to check it manually

Review user access to the cluster and ensure that users are not making use of Kubernetes client certificate authentication.

Remediation

Alternative mechanisms provided by Kubernetes such as the use of OIDC should be implemented in place of client certificates.

Impact Statement

External mechanisms for authentication generally require additional software to be deployed.

Default Value

Client certificate authentication is enabled by default.

Example

No example