Role Binding To Default Service Account

• Query id: 3360c01e-c8c0-4812-96a2-a6329b9b7f9f
• Query name: Role Binding To Default Service Account
• Platform: Terraform
• Severity: Medium
• Category: Insecure Defaults
• URL: Github

Description

No role nor cluster role should bind to a default service account
Documentation

Code samples

Code samples with security vulnerabilities

Positive test num. 1 - tf file

resource "kubernetes_role_binding" "example" {
  metadata {
    name      = "terraform-example"
    namespace = "default"
  }
  role_ref {
    api_group = "rbac.authorization.k8s.io"
    kind      = "Role"
    name      = "admin"
  }
  subject {
    kind      = "User"
    name      = "admin"
    api_group = "rbac.authorization.k8s.io"
  }
  subject {
    kind      = "ServiceAccount"
    name      = "default"
    namespace = "kube-system"
  }
  subject {
    kind      = "Group"
    name      = "system:masters"
    api_group = "rbac.authorization.k8s.io"
  }
}

Code samples without security vulnerabilities

Negative test num. 1 - tf file

resource "kubernetes_role_binding" "example2" {
  metadata {
    name      = "terraform-example"
    namespace = "default"
  }
  role_ref {
    api_group = "rbac.authorization.k8s.io"
    kind      = "Role"
    name      = "admin"
  }
  subject {
    kind      = "User"
    name      = "admin"
    api_group = "rbac.authorization.k8s.io"
  }
  subject {
    kind      = "ServiceAccount"
    name      = "serviceExample"
    namespace = "kube-system"
  }
  subject {
    kind      = "Group"
    name      = "system:masters"
    api_group = "rbac.authorization.k8s.io"
  }
}