Title

The Kubernetes Kubelet must have anonymous authentication disabled. (Cat I impact)

Discussion

A user who has access to the Kubelet essentially has root access to the nodes contained within the Kubernetes Control Plane. To control access, users must be authenticated and authorized. By allowing anonymous connections, the controls put in place to secure the Kubelet can be bypassed. Setting anonymous authentication to "false" also disables unauthenticated requests from kubelets. While there are instances where anonymous connections may be needed (e.g., health checks) and Role-Based Access Controls (RBAC) are in place to limit the anonymous access, this access must be disabled and only enabled when necessary.

Check Content

Run the following command on each Worker Node: ps -ef | grep kubelet Verify that the --anonymous-auth argument exists and is set to "false". If the --anonymous-auth argument exists and is not set to "false", this is a finding. If the --anonymous-auth argument does not exist, check the Control Plane Kubelet config file: On the Kubernetes Control Plane, run the command: ps -ef | grep kubelet Check the config file (path identified by: --config). Verify "authentication: anonymous: enabled=false". If this is not set to "false", this is a finding. If "--anonymous-auth=false" argument does not exist on the worker nodes or "authentication: anonymous: enabled=false" does not exist on the Control Plane, this is a finding.

Fix Text

Edit the Kubernetes Kubelet file in the --config directory on the Kubernetes Control Plane: Set "authentication: anonymous: enabled=false" If using worker node arguments, edit the kubelet service file (identified in the --config directory): On each Worker Node: set the parameter in KUBELET_SYSTEM_PODS_ARGS variable to "--anonymous-auth=false". Reset Kubelet service using the following command: service kubelet restart

Additional Identifiers

Rule ID: SV-242391r879530_rule

Vulnerability ID: V-242391

Group Title: SRG-APP-000033-CTR-000090

Expert Comments

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