Kubernetes etcd must have a certificate for communication.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-242430	CNTR-K8-001520	SV-242430r712646_rule		Medium

Description
Kubernetes stores configuration and state information in a distributed key-value store called etcd. Anyone who can write to etcd can effectively control your Kubernetes cluster. Even just reading the contents of etcd could easily provide helpful hints to a would-be attacker. Using authenticity protection, the communication can be protected against man-in-the-middle attacks/session hijacking and the insertion of false information into sessions. The communication session is protected by utilizing transport encryption protocols, such as TLS. TLS provides the Kubernetes API Server and etcd with a means to be able to authenticate sessions and encrypt traffic. To enable encrypted communication for etcd, the parameter etcd-certfile must be set. This parameter gives the location of the SSL certification file used to secure etcd communication.

Description

Kubernetes stores configuration and state information in a distributed key-value store called etcd. Anyone who can write to etcd can effectively control your Kubernetes cluster. Even just reading the contents of etcd could easily provide helpful hints to a would-be attacker. Using authenticity protection, the communication can be protected against man-in-the-middle attacks/session hijacking and the insertion of false information into sessions. The communication session is protected by utilizing transport encryption protocols, such as TLS. TLS provides the Kubernetes API Server and etcd with a means to be able to authenticate sessions and encrypt traffic. To enable encrypted communication for etcd, the parameter etcd-certfile must be set. This parameter gives the location of the SSL certification file used to secure etcd communication.

STIG	Date
Kubernetes Security Technical Implementation Guide	2021-04-14

Details

Check Text ( C-45705r712644_chk )
Change to the /etc/kubernetes/manifests directory on the Kubernetes Master Node. Run the command: grep -i etcd-certfile * If the setting "etcd-certfile" is not set in the Kubernetes API Server manifest file, this is a finding.

Fix Text (F-45663r712645_fix)
Edit the Kubernetes API Server manifest file in the /etc/kubernetes/manifests directory on the Kubernetes Master Node. Set the value of "--etcd-certfile" to the certificate to be used for communication with etcd.