The Kubernetes Controller Manager must have secure binding.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-242385	CNTR-K8-000310	SV-242385r712511_rule		Medium

Description
Limiting the number of attack vectors and implementing authentication and encryption on the endpoints available to external sources is paramount when securing the overall Kubernetes cluster. The Controller Manager API service exposes port 10252/TCP by default for health and metrics information use. This port does not encrypt or authenticate connections. If this port is exposed externally, an attacker can use this port to attack the entire Kubernetes cluster. By setting the bind address to only localhost (i.e., 127.0.0.1), only those internal services that require health and metrics information can access the Control Manager API.

Description

Limiting the number of attack vectors and implementing authentication and encryption on the endpoints available to external sources is paramount when securing the overall Kubernetes cluster. The Controller Manager API service exposes port 10252/TCP by default for health and metrics information use. This port does not encrypt or authenticate connections. If this port is exposed externally, an attacker can use this port to attack the entire Kubernetes cluster. By setting the bind address to only localhost (i.e., 127.0.0.1), only those internal services that require health and metrics information can access the Control Manager API.

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

Details

Check Text ( C-45660r712509_chk )
Change to the /etc/kubernetes/manifests directory on the Kubernetes Master Node. Run the command: grep -i bind-address * If the setting bind-address is not set to "127.0.0.1" or is not found in the Kubernetes Controller Manager manifest file, this is a finding.

Fix Text (F-45618r712510_fix)
Edit the Kubernetes Controller Manager manifest file in the /etc/kubernetes/manifests directory on the Kubernetes Master Node. Set the argument "--bind-address" to "127.0.0.1".