Headline
CVE-2023-46254: fix(rolebinding-reflector): namespaced name for serviceaccount users · projectcapsule/capsule-proxy@615202f
capsule-proxy is a reverse proxy for Capsule kubernetes multi-tenancy framework. A bug in the RoleBinding reflector used by capsule-proxy gives ServiceAccount tenant owners the right to list Namespaces of other tenants backed by the same owner kind and name. For example consider two tenants solar and wind. Tenant solar, owned by a ServiceAccount named tenant-owner in the Namespace solar. Tenant wind, owned by a ServiceAccount named tenant-owner in the Namespace wind. The Tenant owner solar would be able to list the namespaces of the Tenant wind and vice-versa, although this is not correct. The bug introduces an exfiltration vulnerability since allows the listing of Namespace resources of other Tenants, although just in some specific conditions: 1. capsule-proxy runs with the --disable-caching=false (default value: false) and 2. Tenant owners are ServiceAccount, with the same resource name, but in different Namespaces. This vulnerability doesn’t allow any privilege escalation on the outer tenant Namespace-scoped resources, since the Kubernetes RBAC is enforcing this. This issue has been addressed in version 0.4.5. Users are advised to upgrade. There are no known workarounds for this vulnerability.
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@@ -61,10 +61,12 @@ func (r *RoleBindingReflector) GetUserNamespacesFromRequest(req request.Request)
if strings.HasPrefix(username, serviceaccount.ServiceAccountUsernamePrefix) {
userOwnerKind = capsulev1beta2.ServiceAccountOwner
_, username, err = serviceaccount.SplitUsername(username)
if err != nil {
return nil, errors.Wrap(err, “Unable to parse serviceAccount name”)
namespace, name, splitErr := serviceaccount.SplitUsername(username)
if splitErr != nil {
return nil, errors.Wrap(splitErr, “Unable to parse serviceAccount name”)
}
username = fmt.Sprintf("%s-%s", namespace, name)
}
userRoleBindings, err = r.store.ByIndex(subjectIndex, fmt.Sprintf("%s-%s", userOwnerKind, username))
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@@ -102,7 +104,15 @@ func OwnerRoleBindingsIndexFunc(obj interface{}) (result []string, err error) {
rb := obj.(*rbacv1.RoleBinding)
for _, subject := range rb.Subjects {
result = append(result, fmt.Sprintf("%s-%s", subject.Kind, subject.Name))
parts := []string{subject.Kind}
if len(subject.Namespace) > 0 {
parts = append(parts, subject.Namespace)
}
parts = append(parts, subject.Name)
result = append(result, strings.Join(parts, "-"))
}
return result, nil
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### Summary A bug in the RoleBinding reflector used by `capsule-proxy` gives ServiceAccount tenant owners the right to list Namespaces of other tenants backed by the same owner kind and name. ### Details - Tenant `solar`, owned by a ServiceAccount named `tenant-owner` in the Namespace `solar` - Tenant `wind`, owned by a ServiceAccount named `tenant-owner` in the Namespace `wind` > Please, notice the same ServiceAccount name, although in different namespaces. The Tenant owner `solar` would be able to list the namespaces of the Tenant `wind` and vice-versa, although this is not correct. The bug introduces an exfiltration vulnerability since allows the listing of Namespace resources of other Tenants, although just in some specific conditions: 1. `capsule-proxy` runs with the `--disable-caching=false` (default value: `false`) 2. Tenant owners are ServiceAccount, with the same resource name, but in different Namespaces. The CVE doesn't allow any privilege escalation on the outer ten...