Summary
Dear kanister maintainers: I am Nanzi Yang, a PostDoc of UMN. I find several potential risks of kanister which can be leveraged to make a cluster-level privilege escalation.
Details
The kanister has a deployment called default-kanister-operator, which is bound with a ClusterRole called edit via ClusterRoleBinding(https://github.com/kanisterio/kanister/blob/master/helm/kanister-operator/templates/rbac.yaml#L49). The "edit" ClusterRole is one of Kubernetes default-created ClusterRole, and it have create/patch/udpate verbs of daemonset resources, create verb of serviceaccount/token resources, and impersonate verb of serviceaccounts resources. If a malicious user can access the worker node which has this component, he/she can:
For the create/patch/update verbs of daemonset resources, the malicious user can abuse it to create or modify a set of Pods to mount a high-privilege service account (e.g., the cluster-admin service account). After that, he/she can abuse the high-privilege SA token of created Pod to take over the whole cluster.
For the create verb of serviceaccount/token resources, a malicious user can abuse this permission to generate new Service Account tokens and use them to operate with high-privilege roles, such as cluster administrators. These tokens can be used to access and manipulate any resources within the cluster.
For the impersonate verb of serviceaccounts resources, a malicious user can impersonate high-privilege Service Accounts, thereby gaining access to roles such as cluster administrators. This enables the attacker to perform all actions that the high-privilege account can, including creating, modifying, and deleting critical resources within the cluster.
PoC
We have discussed in the "Details" section
Impact
Privilege escalation
Mitigation
Currently kanister helm chart provides rbac.create flag (true by default), which controls whether the rbac rules for kanister service account will be created https://github.com/kanisterio/kanister/blob/master/helm/kanister-operator/values.yaml#L17
If this value set to false, the user needs to create rbac rules themselves and they can limit the role bindings for kanister service account, for example scope it to specific namespace.
Service account can also be configured via helm https://github.com/kanisterio/kanister/blob/master/helm/kanister-operator/values.yaml#L19
younaman Reporter
Summary
Dear kanister maintainers: I am Nanzi Yang, a PostDoc of UMN. I find several potential risks of kanister which can be leveraged to make a cluster-level privilege escalation.
Details
The kanister has a deployment called default-kanister-operator, which is bound with a ClusterRole called edit via ClusterRoleBinding(https://github.com/kanisterio/kanister/blob/master/helm/kanister-operator/templates/rbac.yaml#L49). The "edit" ClusterRole is one of Kubernetes default-created ClusterRole, and it have create/patch/udpate verbs of daemonset resources, create verb of serviceaccount/token resources, and impersonate verb of serviceaccounts resources. If a malicious user can access the worker node which has this component, he/she can:
For the create/patch/update verbs of daemonset resources, the malicious user can abuse it to create or modify a set of Pods to mount a high-privilege service account (e.g., the cluster-admin service account). After that, he/she can abuse the high-privilege SA token of created Pod to take over the whole cluster.
For the create verb of serviceaccount/token resources, a malicious user can abuse this permission to generate new Service Account tokens and use them to operate with high-privilege roles, such as cluster administrators. These tokens can be used to access and manipulate any resources within the cluster.
For the impersonate verb of serviceaccounts resources, a malicious user can impersonate high-privilege Service Accounts, thereby gaining access to roles such as cluster administrators. This enables the attacker to perform all actions that the high-privilege account can, including creating, modifying, and deleting critical resources within the cluster.
PoC
We have discussed in the "Details" section
Impact
Privilege escalation
Mitigation
Currently kanister helm chart provides rbac.create flag (true by default), which controls whether the rbac rules for kanister service account will be created https://github.com/kanisterio/kanister/blob/master/helm/kanister-operator/values.yaml#L17
If this value set to false, the user needs to create rbac rules themselves and they can limit the role bindings for kanister service account, for example scope it to specific namespace.
Service account can also be configured via helm https://github.com/kanisterio/kanister/blob/master/helm/kanister-operator/values.yaml#L19