Oauth tokens are not encrypted when encryption of data at rest is enabled. An attacker with access to a backup could obtain oauth tokens and use them to log into the cluster as any user who had logged into the cluster via the webui.
Name: Stefan Schimanski (Red Hat)
If you have made a vulnerable backup public you can revoke leaked OAuth tokens by deleting them with the OpenShift API.
To be more precise, this affects OAuthAccessToken and OAuthAuthorizeToken in the auth.openshift.io API group.
This issue only affects OpenShift Container Platform when the 'encryption at rest' feature enabled, see https://access.redhat.com/documentation/en-us/openshift_container_platform/4.3/html/authentication/encrypting-etcd. When backing up the encrypted data the keys should be stored separately to the data, making backups the most likely target of this attack.