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V-254561

CAT I (High)

The Kubernetes kubelet must enable explicit authorization.

Rule ID

SV-254561r1137639_rule

STIG

Rancher Government Solutions RKE2 Security Technical Implementation Guide

Version

V2R6

CCIs

CCI-000213

Discussion

Kubelet is the primary agent on each node. The API server communicates with each kubelet to perform tasks such as starting/stopping pods. By default, kubelets allow all authenticated requests, even anonymous ones, without requiring any authorization checks from the API server. This default behavior bypasses any authorization controls put in place to limit what users may perform within the Kubernetes cluster. To change this behavior, the default setting of AlwaysAllow for the authorization mode must be set to "Webhook".

Check Content

Ensure authorization-mode is set correctly in the kubelet on each rke2 node.

Run this command on each node:
/bin/ps -ef | grep kubelet | grep -v grep

If --authorization-mode is not set to "Webhook" or is not configured, this is a finding.

Fix Text

Edit the RKE2 Configuration File /etc/rancher/rke2/config.yaml on every RKE2 node and set the following "kubelet-arg" argument:

- authorization-mode=Webhook

Once the configuration file is updated, restart the RKE2 Server or Agent. Run the command:
systemctl restart rke2-server or systemctl restart rke2-agent