Service providers may operate one or more services configured to detect requests generated by automated agents. A CAPTCHA may be transmitted in response to requests generated by automated agents. The CAPTCHAs may be included in a modal pop-up box configured to be displayed by a client application displaying a webpage to a customer of the service provider. Furthermore, the CAPTCHAs included in the modal pop-up box may be rendered inactive and caused not to be displayed by client application executing the webpage. Submitted solutions to CAPTCHAs may be presented with a cookie that enables access to resources of the service provider without restriction. Cookies may be tracked and their use may be used to detect automated agent activity.