The Kubernetes API server must have the insecure port flag disabled.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-242386	CNTR-K8-000320	SV-242386r712514_rule		High

Description
By default, the API server will listen on two ports. One port is the secure port and the other port is called the "localhost port". This port is also called the "insecure port", port 8080. Any requests to this port bypass authentication and authorization checks. If this port is left open, anyone who gains access to the host on which the master is running can bypass all authorization and authentication mechanisms put in place, and have full control over the entire cluster. Close the insecure port by setting the API server's --insecure-port flag to "0", ensuring that the --insecure-bind-address is not set.

Description

By default, the API server will listen on two ports. One port is the secure port and the other port is called the "localhost port". This port is also called the "insecure port", port 8080. Any requests to this port bypass authentication and authorization checks. If this port is left open, anyone who gains access to the host on which the master is running can bypass all authorization and authentication mechanisms put in place, and have full control over the entire cluster. Close the insecure port by setting the API server's --insecure-port flag to "0", ensuring that the --insecure-bind-address is not set.

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

Details

Check Text ( C-45661r712512_chk )
Change to the /etc/kubernetes/manifests directory on the Kubernetes Master Node. Run the command: grep -i insecure-port * If the setting insecure-port is not set to "0" or is not configured in the Kubernetes API server manifest file, this is a finding.

Fix Text (F-45619r712513_fix)
Edit the Kubernetes API Server manifest file in the /etc/kubernetes/manifests directory on the Kubernetes Master Node. Set the argument --insecure-port to "0".