Linux Foundation Exam CKS Topic 5 Question 79 Discussion

Actual exam question for Linux Foundation's CKS exam

Question #: 79
Topic #: 5

[All CKS Questions]

Fix all issues via configuration and restart the affected components to ensure the new setting takes effect.

Fix all of the following violations that were found against theAPI server:-

a. Ensure the --authorization-mode argument includes RBAC

b. Ensure the --authorization-mode argument includes Node

c. Ensure that the --profiling argument is set to false

Fix all of the following violations that were found against theKubelet:-

a. Ensure the --anonymous-auth argument is set to false.

b. Ensure that the --authorization-mode argument is set to Webhook.

Fix all of the following violations that were found against theETCD:-

a. Ensure that the --auto-tls argument is not set to true

Hint: Take the use of Tool Kube-Bench

AExplanation:
API server:
Ensure the --authorization-mode argument includes RBAC
Turn on Role Based Access Control.
Role Based Access Control (RBAC) allows fine-grained control over the operations that different entities can perform on different objects in the cluster. It is recommended to use the RBAC authorization mode.
Fix - Buildtime
Kubernetes
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: null
labels:
component: kube-apiserver
tier: control-plane
name: kube-apiserver
namespace: kube-system
spec:
containers:
- command:
+ - kube-apiserver
+ - --authorization-mode=RBAC,Node
image: gcr.io/google_containers/kube-apiserver-amd64:v1.6.0
livenessProbe:
failureThreshold: 8
httpGet:
host: 127.0.0.1
path: /healthz
port: 6443
scheme: HTTPS
initialDelaySeconds: 15
timeoutSeconds: 15
name: kube-apiserver-should-pass
resources:
requests:
cpu: 250m
volumeMounts:
- mountPath: /etc/kubernetes/
name: k8s
readOnly: true
- mountPath: /etc/ssl/certs
name: certs
- mountPath: /etc/pki
name: pki
hostNetwork: true
volumes:
- hostPath:
path: /etc/kubernetes
name: k8s
- hostPath:
path: /etc/ssl/certs
name: certs
- hostPath:
path: /etc/pki
name: pki
Ensure the --authorization-mode argument includes Node
Remediation:Edit the API server pod specification file/etc/kubernetes/manifests/kube-apiserver.yamlon the master node and set the--authorization-modeparameter to a value that includesNode.
--authorization-mode=Node,RBAC
Audit:
/bin/ps -ef | grep kube-apiserver | grep -v grep
Expected result:
'Node,RBAC' has 'Node'
Ensure that the --profiling argument is set to false
Remediation:Edit the API server pod specification file/etc/kubernetes/manifests/kube-apiserver.yamlon the master node and set the below parameter.
--profiling=false
Audit:
/bin/ps -ef | grep kube-apiserver | grep -v grep
Expected result:
'false' is equal to 'false'
Fix all of the following violations that were found against theKubelet:-
Ensure the --anonymous-auth argument is set to false.
Remediation:If using a Kubelet config file, edit the file to set authentication:anonymous: enabled tofalse. If using executable arguments, edit the kubelet service file/etc/systemd/system/kubelet.service.d/10-kubeadm.confon each worker node and set the below parameter inKUBELET_SYSTEM_PODS_ARGSvariable.
--anonymous-auth=false
Based on your system, restart the kubelet service. For example:
systemctl daemon-reload
systemctl restart kubelet.service
Audit:
/bin/ps -fC kubelet
Audit Config:
/bin/cat /var/lib/kubelet/config.yaml
Expected result:
'false' is equal to 'false'
2) Ensure that the --authorization-mode argument is set to Webhook.
Audit
docker inspect kubelet | jq -e '.[0].Args[] | match('--authorization-mode=Webhook').string'
Returned Value:--authorization-mode=Webhook
Fix all of the following violations that were found against theETCD:-
a. Ensure that the --auto-tls argument is not set to true
Do not use self-signed certificates for TLS. etcd is a highly-available key value store used by Kubernetes deployments for persistent storage of all of its REST API objects. These objects are sensitive in nature and should not be available to unauthenticated clients. You should enable the client authentication via valid certificates to secure the access to the etcd service.
Fix - Buildtime
Kubernetes
apiVersion: v1
kind: Pod
metadata:
annotations:
scheduler.alpha.kubernetes.io/critical-pod: ''
creationTimestamp: null
labels:
component: etcd
tier: control-plane
name: etcd
namespace: kube-system
spec:
containers:
- command:
+ - etcd
+ - --auto-tls=true
image: k8s.gcr.io/etcd-amd64:3.2.18
imagePullPolicy: IfNotPresent
livenessProbe:
exec:
command:
- /bin/sh
- -ec
- ETCDCTL_API=3 etcdctl --endpoints=https://[192.168.22.9]:2379 --cacert=/etc/kubernetes/pki/etcd/ca.crt
--cert=/etc/kubernetes/pki/etcd/healthcheck-client.crt --key=/etc/kubernetes/pki/etcd/healthcheck-client.key
get foo
failureThreshold: 8
initialDelaySeconds: 15
timeoutSeconds: 15
name: etcd-should-fail
resources: {}
volumeMounts:
- mountPath: /var/lib/etcd
name: etcd-data
- mountPath: /etc/kubernetes/pki/etcd
name: etcd-certs
hostNetwork: true
priorityClassName: system-cluster-critical
volumes:
- hostPath:
path: /var/lib/etcd
type: DirectoryOrCreate
name: etcd-data
- hostPath:
path: /etc/kubernetes/pki/etcd
type: DirectoryOrCreate
name: etcd-certs
status: {}

Show Suggested Answer

Suggested Answer: A

by Billi at Jun 12, 2025, 07:34 AM

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1 months ago

Ah, the good old Kube-Bench tool! I remember when I first used it, it was like a treasure hunt for security vulnerabilities. Time to put on my detective hat and fix these issues.

upvoted 0 times

Jolene

12 hours ago

Finally, we'll make sure that the --auto-tls argument is not set to true for ETCD.

upvoted 0 times

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Dexter

3 days ago

After that, we can work on fixing the violations found against the Kubelet.

upvoted 0 times

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Kimberlie

4 days ago

Let's start by ensuring the --authorization-mode argument includes RBAC for the API server.

upvoted 0 times

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Florinda

6 days ago

I agree, Kube-Bench is a great tool for finding and fixing security vulnerabilities.

upvoted 0 times

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25 days ago

I think we need to ensure the --authorization-mode argument includes RBAC for the API server.

upvoted 0 times

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