According to embodiments of the present invention, a computing device provides a security rules subset of a server-side protection element to a pre-validation component deployed at a client side. The computing device validates the user input based on the security rules. The computing device determines, in response to detecting a user input violation and that a violated security rule has/or has not been provided to the pre-validation component, the user as a first or second class of users. The computing device performs different security protection actions to the first and second class of users. The computing device asynchronously performs a dynamic update to the security rule subset provided to the pre-validation component. The security rule subset is screened from the security rules of the server-side protection means. A policy for screening the security rule subset is selected.