Free CKS – Certified Kubernetes Security Specialist (CKS) Exam Practice Test Question

Reference / correct answer:

Reference / correct answer:

1. For Dockerfile: Fix the image version & user name in Dockerfile2. For mydeployment.yaml : Fix security contexts

Explanation

[desk@cli] $ vim /home/cert_masters/Dockerfile

FROM ubuntu:latest # Remove this

FROM ubuntu:18.04 # Add this

USER root # Remove this

USER nobody # Add this

RUN apt get install -y lsof=4.72 wget=1.17.1 nginx=4.2

ENV ENVIRONMENT=testing

USER root # Remove this

USER nobody # Add this

CMD ["nginx -d"]

[desk@cli] $ vim /home/cert_masters/mydeployment.yaml

apiVersion: apps/v1

kind: Deployment

metadata:

creationTimestamp: null

labels:

app: kafka

name: kafka

spec:

replicas: 1

selector:

matchLabels:

app: kafka

strategy: {}

template:

metadata:

creationTimestamp: null

labels:

app: kafka

spec:

containers:

- image: bitnami/kafka

name: kafka

volumeMounts:

- name: kafka-vol

mountPath: /var/lib/kafka

securityContext:

{"capabilities":{"add":["NET_ADMIN"],"drop":["all"]},"privileged": True,"readOnlyRootFilesystem": False, "runAsUser": 65535} # Delete This

{"capabilities":{"add":["NET_ADMIN"],"drop":["all"]},"privileged": False,"readOnlyRootFilesystem": True, "runAsUser": 65535} # Add This

resources: {}

volumes:

- name: kafka-vol

emptyDir: {}

status: {}

Pictorial View:[desk@cli] $ vim /home/cert_masters/mydeployment.yaml

Reference: https://kubernetes.io/docs/concepts/policy/pod-security-policy/

Reference / correct answer:

Reference / correct answer:

Create psp to disallow privileged container

k create sa psp-denial-sa -n development

namespace: development

Explanation

master1 $ vim psp.yaml

apiVersion: policy/v1beta1

kind: PodSecurityPolicy

metadata:

name: deny-policy

spec:

privileged: false # Don't allow privileged pods!

seLinux:

rule: RunAsAny

supplementalGroups:

rule: RunAsAny

runAsUser:

rule: RunAsAny

fsGroup:

rule: RunAsAny

volumes:

- '*'

master1 $ vim cr1.yaml

apiVersion: rbac.authorization.k8s.io/v1

kind: ClusterRole

metadata:

name: deny-access-role

rules:

- apiGroups: ['policy']

resources: ['podsecuritypolicies']

verbs: ['use']

resourceNames:

- “deny-policy”

master1 $ k create sa psp-denial-sa -n developmentmaster1 $ vim cb1.yaml

apiVersion: rbac.authorization.k8s.io/v1

kind: ClusterRoleBinding

metadata:

name: restrict-access-bing

roleRef:

kind: ClusterRole

name: deny-access-role

apiGroup: rbac.authorization.k8s.io

subjects:

# Authorize specific service accounts:

- kind: ServiceAccount

name: psp-denial-sa

namespace: development

master1 $ k apply -f psp.yamlmaster1 $ k apply -f cr1.yamlmaster1 $ k apply -f cb1.yamlReference: https://kubernetes.io/docs/concepts/policy/pod-security-policy/

Reference / correct answer:

apiVersion: networking.k8s.io/v1

kind: NetworkPolicy

metadata:

name: network-policy

spec:

podSelector: {} #selects all the pods in the namespace deployed

policyTypes:

- Ingress

ingress:

- ports: #in input traffic allowed only through 80 port only

- protocol: TCP

port: 80

Reference / correct answer:

Reference / correct answer:

a) Create a PSP that will prevent the creation of privileged pods in the namespace.

$ cat clusterrole-use-privileged.yaml

---

apiVersion: rbac.authorization.k8s.io/v1

kind: ClusterRole

metadata:

name: use-privileged-psp

rules:

- apiGroups: ['policy']

resources: ['podsecuritypolicies']

verbs: ['use']

resourceNames:

- default-psp

---

apiVersion: rbac.authorization.k8s.io/v1

kind: RoleBinding

metadata:

name: privileged-role-bind

namespace: psp-test

roleRef:

apiGroup: rbac.authorization.k8s.io

kind: ClusterRole

name: use-privileged-psp

subjects:

- kind: ServiceAccount

name: privileged-sa

$ kubectl -n psp-test apply -f clusterrole-use-privileged.yaml

After a few moments, the privileged Pod should be created.

b) Create a new PodSecurityPolicy named prevent-privileged-policy which prevents the creation of privileged pods.

apiVersion: policy/v1beta1

kind: PodSecurityPolicy

metadata:

name: example

spec:

privileged: false # Don't allow privileged pods!

# The rest fills in some required fields.

seLinux:

rule: RunAsAny

supplementalGroups:

rule: RunAsAny

runAsUser:

rule: RunAsAny

fsGroup:

rule: RunAsAny

volumes:

- '*'

And create it with kubectl:

kubectl-admin create -f example-psp.yaml

Now, as the unprivileged user, try to create a simple pod:

kubectl-user create -f- <<>

apiVersion: v1

kind: Pod

metadata:

name: pause

spec:

containers:

- name: pause

image: k8s.gcr.io/pause

EOF

The output is similar to this:

Error from server (Forbidden): error when creating "STDIN": pods "pause" is forbidden: unable to validate against any pod security policy: []

c) Create a new ServiceAccount named psp-sa in the namespace default.

$ cat clusterrole-use-privileged.yaml

---

apiVersion: rbac.authorization.k8s.io/v1

kind: ClusterRole

metadata:

name: use-privileged-psp

rules:

- apiGroups: ['policy']

resources: ['podsecuritypolicies']

verbs: ['use']

resourceNames:

- default-psp

---

apiVersion: rbac.authorization.k8s.io/v1

kind: RoleBinding

metadata:

name: privileged-role-bind

namespace: psp-test

roleRef:

apiGroup: rbac.authorization.k8s.io

kind: ClusterRole

name: use-privileged-psp

subjects:

- kind: ServiceAccount

name: privileged-sa

$ kubectl -n psp-test apply -f clusterrole-use-privileged.yaml

After a few moments, the privileged Pod should be created.

d) Create a new ClusterRole named prevent-role, which uses the newly created Pod Security Policy prevent-privileged-policy.

apiVersion: policy/v1beta1

kind: PodSecurityPolicy

metadata:

name: example

spec:

privileged: false # Don't allow privileged pods!

# The rest fills in some required fields.

seLinux:

rule: RunAsAny

supplementalGroups:

rule: RunAsAny

runAsUser:

rule: RunAsAny

fsGroup:

rule: RunAsAny

volumes:

- '*'

And create it with kubectl:

kubectl-admin create -f example-psp.yaml

Now, as the unprivileged user, try to create a simple pod:

kubectl-user create -f- <<>

apiVersion: v1

kind: Pod

metadata:

name: pause

spec:

containers:

- name: pause

image: k8s.gcr.io/pause

EOF

The output is similar to this:

Error from server (Forbidden): error when creating "STDIN": pods "pause" is forbidden: unable to validate against any pod security policy: []

e) Create a new ClusterRoleBinding named prevent-role-binding, which binds the created ClusterRole prevent-role to the created SA psp-sa.

apiVersion: rbac.authorization.k8s.io/v1

# This role binding allows "jane" to read pods in the "default" namespace.

# You need to already have a Role named "pod-reader" in that namespace.

kind: RoleBinding

metadata:

name: read-pods

namespace: default

subjects:

# You can specify more than one "subject"

- kind: User

name: jane # "name" is case sensitive

apiGroup: rbac.authorization.k8s.io

roleRef:

# "roleRef" specifies the binding to a Role / ClusterRole

kind: Role #this must be Role or ClusterRole

name: pod-reader # this must match the name of the Role or ClusterRole you wish to bind to

apiGroup: rbac.authorization.k8s.io

apiVersion: rbac.authorization.k8s.io/v1

kind: Role

metadata:

namespace: default

name: pod-reader

rules:

- apiGroups: [""] # "" indicates the core API group

resources: ["pods"]

verbs: ["get", "watch", "list"]

Reference / correct answer:

Reference: https://github.com/aquasecurity/trivy

Reference / correct answer:

Reference / correct answer:

Reference: https://kubernetes.io/docs/tutorials/clusters/apparmor/