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Profile applicability: Level 1 - Master Node
etcd should be configured to make use of TLS encryption for client connections.
etcd is a highly-available key value store used by Kubernetes deployments for persistent storage of all of its REST API objects. These objects are sensitive in nature and should be protected by client authentication. This requires the API server to identify itself to the etcd server using a SSL Certificate Authority file.
Note
Note
By default, --etcd-cafile is not set.

Impact

TLS and client certificate authentication must be configured for etcd.

Audit

Run the following command on the Control Plane node:
ps -ef | grep kube-apiserver
Verify that the --etcd-cafile argument exists and it is set as appropriate.

Remediation

Follow the Kubernetes documentation and set up the TLS connection between the apiserver and etcd. Then, edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the etcd certificate authority file parameter.
--etcd-cafile=<path/to/ca-file>