public class Global : System.Web.HttpApplication
    {
        // other methods snipped...
        protected void Application_AuthenticateRequest(object sender, EventArgs e)
        {
            HttpCookie ticketCookie = Context.Request.Cookies[FormsAuthentication.FormsCookieName];
            if (null == ticketCookie)
            {
                return;
            }

            FormsAuthenticationTicket ticket = FormsAuthentication.Decrypt(ticketCookie.Value);
            if (null != ticket)
            {
                HttpContext.Current.User = new GenericPrincipal(new FormsIdentity(ticket), null);
            }
        }
    }