Conditionally disable ASP.NET MVC Controller

What is the best way to disable ASP.NET MVC controller conditionally?

I want to have an access to the controller actions if some value in web.config is "true" and 404 if it's "false"

Should I write my own attribute?

UPDATE: Looking for more elegant solution than action filter attribute (with an ability to pass not constant parameter to attribute constructor)

    [AttributeUsage(AttributeTargets.Class, AllowMultiple = true, Inherited = true)]
    public class CloseForSomeSettingAttribute : ActionFilterAttribute
    {
        public override void OnActionExecuting(ActionExecutingContext filterContext)
        {
            bool mySettingValue = MySettingManager.GetMySettingValue();

            if (mySettingValue)
            {
                filterContext.Result = new HttpStatusCodeResult(404);
            }
            else
            {
                base.OnActionExecuting(filterContext);
            }
        }
    }