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Disable anonymous requests to the Kubelet server.
When enabled, requests that are not rejected by other configured authentication methods are treated as anonymous requests. These requests are then served by the Kubelet server. You should rely on authentication to authorize access and disallow anonymous requests.
Note
Note
See the Azure AKS documentation for the default value.

Impact

Anonymous requests will be rejected.

Audit

Audit Method 1
If using a Kubelet configuration file, check that there is an entry for authentication: anonymous: enabled set to false.
  1. SSH to the relevant node.
  2. 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.
  3. Open the Kubelet config file:
    sudo more /etc/kubernetes/kubelet/kubelet-config.json
  4. Verify that the "authentication": { "anonymous": { "enabled": false } } argument is set to false.
Audit Method 2
If using the api configz endpoint, search for the status of authentication... "anonymous":{"enabled":false} by extracting the live configuration from the nodes running kubelet.
  1. Set the local proxy port and the following variables and provide proxy port number and node name:
    kubectl proxy --port=8001 &

export HOSTNAME_PORT=localhost:8001
export NODE_NAME=ip-192.168.31.226.aks.internal

curl -sSL "http://${HOSTNAME_PORT}/api/v1/nodes/${NODE_NAME}/proxy/configz"

Remediation

Remediation Method 1
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:
"anonymous": "enabled": false
Remediation Method 2
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:
--anonymous-auth=false
Remediation Method 3
If using the api configz endpoint, search for the status of "authentication.*anonymous":{"enabled":false}" by extracting the live configuration from the nodes running kubelet. See detailed step-by-step configmap procedures in Reconfigure a Node's Kubelet in a Live Cluster, and then rerun the curl statement from audit process to check for kubelet configuration changes:
kubectl proxy --port=8001 &

export HOSTNAME_PORT=localhost:8001
export NODE_NAME=ip-192.168.31.226.aks.internal

curl -sSL "http://${HOSTNAME_PORT}/api/v1/nodes/${NODE_NAME}/proxy/configz"
For all three remediations: Based on your system, restart the kubelet service and check status:
systemctl daemon-reload
systemctl restart kubelet.service
systemctl status kubelet -l