The Kubernetes Scheduler must have secure binding.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-242384	SRG-APP-000033-CTR-000090	CNTR-K8-000300	SV-242384r960792_rule	2025-02-20	2

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.

ℹ️ Check
Change to the /etc/kubernetes/manifests directory on the Kubernetes Control Plane. 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
Edit the Kubernetes Scheduler manifest file in the /etc/kubernetes/manifests directory on the Kubernetes Control Plane. Set the argument "--bind-address" to "127.0.0.1".