This rule identifies when a Duo user's authentication attempt is denied due to issues related to the endpoint. It captures specific denial reasons such as whether the endpoint is not managed, failed Google verification, is untrusted, or if the trust status could not be determined. Each instance of this event logs the user's details and the endpoint characteristics. The rule highlights security concerns regarding unauthorized or mismanaged devices making authentication requests, emphasizing the importance of endpoint integrity in the authentication process. The expected responses from various tests help validate incidents where authentication fails because of endpoint-related errors, significantly aiding in pinpointing security vulnerabilities and ensuring user verification is performed through valid devices.