Cis Ocp V160 1.2.1

CIS Red Hat OpenShift Container Platform Benchmark v1.6.0 - Control 1.2.1

Profile Applicability

• Level: 1

Description

When anonymous requests to the API server are allowed, they must be authorized.

Rationale

When enabled, requests that are not rejected by other configured authentication methods are treated as anonymous requests. These requests are then served by the API server. You should rely on authentication to authorize anonymous requests.

If you are using RBAC authorization, it is generally considered reasonable to allow anonymous access to the API Server for health checks and discovery purposes, and hence this recommendation is not scored. However, you should consider whether anonymous discovery is an acceptable risk for your purposes.

Impact

Anonymous requests are assigned to the system:unauthenticated group which allows the system to determine which actions are allowed.

Audit Procedure

OpenShift allows anonymous requests (then authorizes them). OpenShift allows anonymous requests to the API server to support information discovery and webhook integrations. OpenShift provides its own fully integrated authentication and authorization mechanism. If no access token or certificate is presented, the authentication layer assigns the system:anonymous virtual user and the system:unauthenticated virtual group to the request. This allows the authorization layer to determine which requests, if any, an anonymous user is allowed to make.

oc get clusterrolebindings -o json | jq '.items[] | select(.subjects[]?.kind == "Group" and .subjects[]?.name == "system:unauthenticated") | .metadata.name' | uniq

Returns what unauthenticated users can do, which is the following:

"self-access-reviewers"
"system:oauth-token-deleters"
"system:openshift:public-info-viewer"
"system:public-info-viewer"
"system:scope-impersonation"
"system:webhooks"

Remediation

None. The default configuration should not be modified.

Default Value

By default, anonymous access is enabled and assigned to the system:unauthenticated group, which allows the system to determine which actions are allowed.

If the default behavior is changed, platform components will not work properly, in particular Elasticsearch and Prometheus. The oauth-proxy deployed as part of these components makes anonymous use of /.well-known/oauth-authorization-server endpoint, granted by system:discovery role.

References

1. https://docs.openshift.com/container-platform/4.5/authentication/understanding-authentication.html
2. https://docs.openshift.com/container-platform/4.5/authentication/using-rbac.html
3. https://docs.openshift.com/container-platform/4.5/operators/operator-reference.html#cluster-authentication-operator_red-hat-operators
4. https://docs.openshift.com/container-platform/4.5/operators/operator-reference.html#kube-apiserver-operator_red-hat-operators
5. https://docs.openshift.com/container-platform/4.5/operators/operator-reference.html#openshift-apiserver-operator_red-hat-operators
6. https://kubernetes.io/docs/reference/command-line-tools-reference/kube-apiserver/
7. https://kubernetes.io/docs/reference/access-authn-authz/authentication/#anonymous-requests

CIS Controls

MITRE ATT&CK Mappings

Profile

Level 1 (Manual)