etcd should use TLS encryption for client connections
Set up the kubernetes integration.
Description
etcd should be configured to make use of TLS encryption for client connections.
Rationale
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.
Audit
Run the following command on the master node:
ps -ef | grep kube-apiserver
Verify that the --etcd-cafile argument exists and it is set as appropriate.
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>
Impact
TLS and client certificate authentication must be configured for etcd.
Default value
By default, --etcd-cafile is not set.
References
- https://kubernetes.io/docs/admin/kube-apiserver/
- https://coreos.com/etcd/docs/latest/op-guide/security.html
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.
