Aspects of the disclosure relate to preventing unauthorized access to secured information systems. A computing platform may receive, from an end user desktop computing device, a request to login to a user account associated with a user account portal. In response to receiving the request, the computing platform may generate an authentication token in an authentication database and may send a notification to at least one registered device linked to the user account. After sending the notification, the computing platform may receive, from the at least one registered device, an authentication response message. If the authentication response message indicates that valid authentication input was received, the computing platform may update the authentication token to indicate that the request to login to the user account has been approved. After updating the authentication token, the computing platform may provide, to the end user desktop computing device, access to a portal interface.