Kubernetes etcd must have a key file for secure communication.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-242431	CNTR-K8-001530	SV-242431r712649_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 a 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-keyfile must be set. This parameter gives the location of the key 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 a 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-keyfile must be set. This parameter gives the location of the key file used to secure etcd communication.

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

Details

Check Text ( C-45706r712647_chk )
Change to the /etc/kubernetes/manifests directory on the Kubernetes Master Node. Run the command: grep -i etcd-keyfile * If the setting "etcd-keyfile" is not configured in the Kubernetes API Server manifest file, this is a finding.

Fix Text (F-45664r712648_fix)
Edit the Kubernetes API Server manifest file in the /etc/kubernetes/manifests directory on the Kubernetes Master Node. Set the value of "--etcd-keyfile" to the certificate to be used for communication with etcd.