The API server should set up TLS connection for client authentication
Set up the kubernetes integration.
Description
Setup TLS connection on the API server.
Rationale
API server communication contains sensitive parameters that should remain encrypted in transit. Configure the API server to serve only HTTPS traffic. If --client-ca-file argument is set, any request presenting a client certificate signed by one of the authorities in the client-ca-file is authenticated with an identity corresponding to the CommonName of the client certificate.
Audit
Run the following command on the master node:
ps -ef | grep kube-apiserver
Verify that the --client-ca-file argument exists and it is set as appropriate.
Follow the Kubernetes documentation and set up the TLS connection on the apiserver. Then, edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the client certificate authority file: --client-ca-file=<path/to/client-ca-file>
Impact
TLS and client certificate authentication must be configured for your Kubernetes cluster deployment.
Default value
By default, --client-ca-file argument is not set.
References
- https://kubernetes.io/docs/admin/kube-apiserver/
- http://rootsquash.com/2016/05/10/securing-the-kubernetes-api/
- https://github.com/kelseyhightower/docker-kubernetes-tls-guide
CIS controls
Version 6 14.2 Encrypt All Sensitive Information Over Less-trusted Networks - All communication of sensitive information over less-trusted networks should be encrypted. Whenever information flows over a network with a lower trust level, the information should be encrypted.
Version 7 14.4 Encrypt All Sensitive Information in Transit - Encrypt all sensitive information in transit.
