cis-k8s-v1120-4-2-7

name	cis-k8s-v1120-4.2.7
description	Ensure that the --hostname-override argument is not set (Manual)
category	cis-k8s
version	1.12.0
author	cyberstrike-official
tags	["cis","kubernetes","worker-nodes","kubelet"]
cis_id	4.2.7
cis_benchmark	CIS Kubernetes Benchmark v1.12.0
tech_stack	["kubernetes"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

CIS Kubernetes Benchmark v1.12.0 - Control 4.2.7

Description

Do not override node hostnames.

Rationale

Overriding hostnames could potentially break TLS setup between the kubelet and the apiserver. Additionally, with overridden hostnames, it becomes increasingly difficult to associate logs with a particular node and process them for security analytics. Hence, you should setup your kubelet nodes with resolvable FQDNs and avoid overriding the hostnames with IPs.

Impact

Some cloud providers may require this flag to ensure that hostname matches names issued by the cloud provider. In these environments, this recommendation should not apply.

Audit Procedure

Step 1: Verify via process arguments

Run the following command on each node:

ps -ef | grep kubelet

Verify that --hostname-override argument does not exist.

Note This setting is not configurable via the Kubelet config file.

Remediation

Edit the kubelet service file /etc/systemd/system/kubelet.service.d/10-kubeadm.conf on each worker node and remove the --hostname-override argument from the KUBELET_SYSTEM_PODS_ARGS variable.

Based on your system, restart the kubelet service. For example:

systemctl daemon-reload
systemctl restart kubelet.service

Default Value

By default, --hostname-override argument is not set.

References

1. https://kubernetes.io/docs/admin/kubelet/
2. https://github.com/kubernetes/kubernetes/issues/22063

CIS Controls

Controls Version	Control	IG 1	IG 2	IG 3
v8	4 Secure Configuration of Enterprise Assets and Software Establish and maintain the secure configuration of enterprise assets (end-user devices, including portable and mobile; network devices; non-computing/IoT devices; and servers) and software (operating systems and applications).
v7	5 Secure Configuration for Hardware and Software on Mobile Devices, Laptops, Workstations and Servers Secure Configuration for Hardware and Software on Mobile Devices, Laptops, Workstations and Servers