cyberstrikeus 4.2.2 Ensure that the --authorization-mode argument is not set to AlwaysAllow (Automated)
Profile Applicability
- Level 1 - Worker Node
Description
Do not allow all requests. Enable explicit authorization.
Rationale
Kubelets, by default, allow all authenticated requests (even anonymous ones) without needing explicit authorization checks from the apiserver. You should restrict this behavior and only allow explicitly authorized requests.
Impact
Unauthorized requests will be denied.
Audit
Run the following command on each node:
ps -ef | grep kubelet
If the --authorization-mode argument is present check that it is not set to AlwaysAllow. If it is not present check that there is a Kubelet config file specified by --config, and that file sets authorization: mode to something other than AlwaysAllow.
It is also possible to review the running configuration of a Kubelet via the /configz endpoint on the Kubelet API port (typically 10250/TCP). Accessing these with appropriate credentials will provide details of the Kubelet's configuration.
Remediation
If using a Kubelet config file, edit the file to set authorization: mode to Webhook.
If using executable arguments, edit the kubelet service file /etc/kubernetes/kubelet.conf on each worker node and set the below parameter in KUBELET_AUTHZ_ARGS variable.
--authorization-mode=Webhook
Based on your system, restart the kubelet service. For example:
systemctl daemon-reload
systemctl restart kubelet.service
Default Value
By default, --authorization-mode argument is set to AlwaysAllow.
References
- https://kubernetes.io/docs/admin/kubelet/
- https://kubernetes.io/docs/admin/kubelet-authentication-authorization/#kubelet-authentication
CIS Controls
| Controls Version | Control | IG 1 | IG 2 | IG 3 |
|---|---|---|---|---|
| v8 | 3.3 Configure Data Access Control Lists - Configure data access control lists based on a user's need to know. Apply data access control lists, also known as access permissions, to local and remote file systems, databases, and applications. | * | * | * |
| v7 | 9.2 Ensure Only Approved Ports, Protocols and Services Are Running - Ensure that only network ports, protocols, and services listening on a system with validated business needs, are running on each system. | * | * |