The Kubernetes Scheduler must have secure binding.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-242384	CNTR-K8-000300	SV-242384r712508_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 Scheduler API service exposes port 10251/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 localhost (i.e., 127.0.0.1), only those internal services that require health and metrics information can access the Scheduler 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 Scheduler API service exposes port 10251/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 localhost (i.e., 127.0.0.1), only those internal services that require health and metrics information can access the Scheduler API.

STIG	Date
Kubernetes Security Technical Implementation Guide	2021-06-17

Details

Check Text ( C-45659r712506_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 Scheduler manifest file, this is a finding.

Fix Text (F-45617r712507_fix)
Edit the Kubernetes Scheduler manifest file in the /etc/kubernetes/manifests directory on the Kubernetes Master Node. Set the argument "--bind-address" to "127.0.0.1".