cis-ocp-v190-1.4.1

CIS Red Hat OpenShift Container Platform Benchmark v1.9.0 - Control 1.4.1

Profile Applicability

• Level: 1

Description

Disable profiling, if not needed.

Rationale

Profiling allows for the identification of specific performance bottlenecks. It generates a significant amount of program data that could potentially be exploited to uncover system and program details. If you are not experiencing any bottlenecks and do not need the profiler for troubleshooting purposes, it is recommended to turn it off to reduce the potential attack surface.

Impact

Profiling information would not be available.

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.

To verify the configuration, run the following command:

Run the following command to check the livenessProbe configuration:

oc -n openshift-kube-scheduler get cm kube-scheduler-pod -o json | jq -r '.data."pod.yaml"' | jq '.spec.containers[].livenessProbe'

Verify the output path is set to healthz.

Run the following command to check the readinessProbe configuration:

oc -n openshift-kube-scheduler get cm kube-scheduler-pod -o json | jq -r '.data."pod.yaml"' | jq '.spec.containers[].readinessProbe'

Verify the output path is set to healthz.

Verify endpoints exist for the scheduler:

oc -n openshift-kube-scheduler describe endpoints

Validate that RBAC is enabled and protects controller endpoints. First, switch to the openshift-kube-scheduler:

oc project openshift-kube-scheduler

Next, get the schedule pod name and port:

export POD=$(oc get pods -l app=openshift-kube-scheduler -o jsonpath='{.items[0].metadata.name}')
export PORT=$(oc get pod $POD -o jsonpath='{.spec.containers[0].livenessProbe.httpGet.port}')

Attempt to make an insecure GET request to the metrics endpoint:

oc rsh $POD curl https://localhost:$PORT/metrics -k

Verify that an HTTP 403 is returned.

Create a test service account:

oc create sa permission-test-sa

Generate a service account token and attempt to access the metrics endpoint:

export SA_TOKEN=$(oc create token permission-test-sa)
oc rsh $POD curl http://localhost:$PORT/metrics -H "Authorization: Bearer $SA_TOKEN" -k

Verify that an HTTP 403 is returned.

Login as a cluster administrator and attempt to access the metrics endpoint:

CLUSTER_ADMIN_TOKEN=$(oc whoami -t)
oc rsh $POD curl https://localhost:$PORT/metrics -H "Authorization: Bearer $CLUSTER_ADMIN_TOKEN" -k

Verify metrics output is returned. Unset environment variables used in the test and delete the test service account:

unset CLUSTER_ADMIN_TOKEN POD PORT SA_TOKEN
oc delete sa permission-test-sa

Remediation

None.

Default Value

By default, profiling is enabled and protected by RBAC.

References

1. https://github.com/openshift/cluster-kube-scheduler-operator
2. https://github.com/openshift/cluster-kube-scheduler-operator/blob/release-4.5/bindata/v4.1.0/kube-scheduler/svc.yaml
3. https://github.com/openshift/cluster-kube-scheduler-operator/blob/release-4.5/bindata/v4.1.0/kube-scheduler/pod.yaml
4. https://github.com/openshift/cluster-kube-scheduler-operator/blob/release-4.5/bindata/v4.1.0/kube-scheduler/pod.yaml#L32-L37
5. https://kubernetes.io/docs/reference/command-line-tools-reference/kube-scheduler/
6. https://github.com/kubernetes/community/blob/master/contributors/devel/sig-scalability/profiling.md

CIS Controls

MITRE ATT&CK Mappings

Profile

Level 1 (Manual)