The Kubernetes kubelet must enable explicit authorization.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-242392	CNTR-K8-000380	SV-242392r712532_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
Kubernetes Security Technical Implementation Guide	2021-04-14

Details

Check Text ( C-45667r712530_chk )
Change to the /etc/sysconfig/ directory on the Kubernetes Master Node. Run the command: grep -i authorization-mode kubelet On each Worker node, change to the /etc/sysconfig/ directory. Run the command: grep -i authorization-mode kubelet If authorization-mode is missing or is set to "AllowAlways" on the Master node or any of the Worker nodes, this is a finding.

Fix Text (F-45625r717029_fix)
Edit the Kubernetes Kubelet file in the/etc/sysconfig/ directory on the Kubernetes Master and Worker nodes. Set the argument --authorization-mode to "Webhook". Restart each kubelet service after the change is made using the command: service kubelet restart