3.2.4 - Ensure that the --read-only-port is secured (Automated)

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Profile applicability: Level 1

Disable the read-only port.

The Kubelet process provides a read-only API in addition to the main Kubelet API. Unauthenticated access is provided to this read-only API which could possibly retrieve potentially sensitive information about the cluster.

Note

See the Azure AKS documentation for the default value.

Impact

Removal of the read-only port will require that any service which made use of it will need to be re-configured to use the main Kubelet API.

Audit

If using a Kubelet configuration file, check that there is an entry for authentication:anonymous: enabled set to 0.

SSH to the relevant node.
Run the following command on each node to find the appropriate Kubelet config file:
```
ps -ef | grep kubelet
```
The output should return something similar to --config /etc/kubernetes/kubelet/kubelet-config.json, which is the location of the Kubelet config file.

Open the Kubelet config file:

cat /etc/kubernetes/kubelet/kubelet-config.json

Verify that the --read-only-port argument exists and is set to 0.

If the --read-only-port argument is not present, check that there is a Kubelet config file specified by --config. Check that if there is a readOnlyPort entry in the file, it is set to 0.

Remediation

If modifying the Kubelet config file, edit the kubelet-config.json file /etc/kubernetes/kubelet/kubelet-config.json and set the below parameter to false:

readOnlyPort to 0

If using executable arguments, edit the kubelet service file /etc/systemd/system/kubelet.service.d/10-kubelet-args.conf on each worker node and add the below parameter at the end of the KUBELET_ARGS variable string:

--read-only-port=0

For all remediations: Based on your system, restart the kubelet service and check status:

systemctl daemon-reload
systemctl restart kubelet.service
systemctl status kubelet -l