cis-ocp-v170-1-4-2

name	cis-ocp-v170-1.4.2
description	Verify scheduler API service protected by RBAC (Manual)
category	cis-openshift
version	1.7.0
author	cyberstrike-official
tags	["cis","openshift","kubernetes","redhat","control-plane","scheduler"]
cis_id	1.4.2
cis_benchmark	CIS Red Hat OpenShift Container Platform Benchmark v1.7.0
tech_stack	["kubernetes","openshift","redhat"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

CIS Red Hat OpenShift Container Platform Benchmark v1.7.0 - Control 1.4.2

Profile Applicability

• Level: 1

Description

Do not bind the scheduler service to non-loopback insecure addresses.

Rationale

The Scheduler API service which runs on port 10251/TCP by default is used for health and metrics information and is available without authentication or encryption. As such it should only be bound to a localhost interface, to minimize the cluster's attack surface.

Impact

None.

Audit Procedure

In OpenShift 4, The Kubernetes Scheduler operator manages and updates the Kubernetes Scheduler deployed on top of OpenShift. By default, the operator exposes metrics via metrics service. The metrics are collected from the Kubernetes Scheduler operator. Profiling data is sent to healthzPort, the port of the localhost healthz endpoint. Changing this value may disrupt components that monitor the kubelet health. The default healthz port value is 10251, and the healthz bindAddress is 127.0.0.1. To ensure the collected data is not exploited, profiling endpoints are secured via RBAC (see cluster-debugger role). By default, the profiling endpoints are accessible only by users bound to cluster-admin or cluster-debugger role. Profiling can not be disabled.

The bind-address argument is not used. Both authentication and authorization are in place.

Run the following command to verify the schedule endpoints:

oc -n openshift-kube-scheduler describe endpoints

Verify the bind-address and port arguments are not used:

oc -n openshift-kube-scheduler get cm kube-scheduler-pod -o json | jq -r '.data."pod.yaml"' | jq '.spec.containers[]|select(.name=="kube-scheduler")|.args'

Verify the metrics endpoint is protected by RBAC. First, find the schedule pod information:

oc project openshift-kube-scheduler
export POD=$(oc get pods -l app=openshift-kube-scheduler -o jsonpath='{.items[0].metadata.name}')
export POD_IP=$(oc get pods -l app=openshift-kube-scheduler -o jsonpath='{.items[0].status.podIP}')
export PORT=$(oc get pod  -o jsonpath=)