Default Kubernetes service accounts are actively used by bounding to a role or cluster role

Description

Every Kubernetes installation has a service account called default that is associated with every running pod. Similarly, to enable pods to make calls to the internal API Server endpoint, there is a ClusterIP service called Kubernetes. This combination makes it possible for internal processes to call the API endpoint. We recommend that users create their own user-managed service accounts and grant the appropriate roles to each service account.

Code Example

apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: <name>
subjects:
-- kind: ServiceAccount
-  name: default

Remediation

Kubernetes

Option 1

• Resource: ServiceAccount
• Arguments: If service name is set to default, automountServiceAccountToken should be set to false in order to opt out of automounting API credentials for a service account.

[source,default service]

apiVersion: v1 kind: ServiceAccount metadata: name: default

• automountServiceAccountToken: false

---

[source,non-default service]

apiVersion: v1 kind: ServiceAccount metadata:

• name: <service name>

---

Option 2

• Resource: RoleBinding / ClusterRoleBinding
• Arguments: RoleBinding grants the permissions defined in a role to a user or set of users within a specific namespace. ClusterRoleBinding grants that access cluster-wide. To avoid activating the default service account, it should not be used as a subject in RoleBinding or ClusterRoleBinding resources.

Rule Details

Field	Value
ID	IAC-1120
Severity	LOW
IaC Type	Kubernetes
Frameworks	Kubernetes,
Checkov ID	CKV_K8S_42

References

• Checkov Rule

---