The Kubernetes kubelet must enable explicit authorization.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-254561	CNTR-R2-000150	SV-254561r879530_rule		High

Description
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".

Description

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".

STIG	Date
Rancher Government Solutions RKE2 Security Technical Implementation Guide	2023-02-27

Details

Check Text ( C-58045r870255_chk )
Ensure authorization-mode is set correctly in the kubelet. 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 (F-57994r859252_fix)
Edit the Kubernetes Kubelet file etc/rancher/rke2/config.yaml on the RKE2 Control Plane and set the following: --authorization-mode=Webhook Once configuration file is updated, restart the RKE2 Agent. Run the command: systemctl restart rke2-agent