Create Custom Authorization Filter using MVC

public class CustomAuthFilter : AuthorizeAttribute
{
public override void OnAuthorization(AuthorizationContext filterContext)
{
if (check if Unauthorised)
{
// do your stuff
filterContext.HttpContext.Response.Redirect(“~/Unauthorised/Index”);

}
}
}

and then you can use in controller for authorizing your ActionResult using [CustomAuthFilter]