At least initially blocking client download of certain content and injecting a user verification step for such downloads is disclosed. In some embodiments, a notification page with an option to accept a response from a server is provided to a client, an indication of user selection of the option to accept in the notification page is received from the client, and requested content received from the server is provided to the client. Injecting a user verification step via the notification page before providing requested content facilitates protecting the client from security threats.