Helps to protect against XSRF attacks

AntiXsrf.Master.cs

public partial class HuntGroup : System.Web.UI.MasterPage
    {
        private const string AntiXsrfTokenKey = "__AntiXsrfToken";
        private const string AntiXsrfUserNameKey = "__AntiXsrfUserName";
        private string _antiXsrfTokenValue;

        protected void Page_Init(object sender, EventArgs e)
        {
            // The code below helps to protect against XSRF attacks
            var requestCookie = Request.Cookies[AntiXsrfTokenKey];
            Guid requestCookieGuidValue;
            if (requestCookie != null && Guid.TryParse(requestCookie.Value, out requestCookieGuidValue))
            {
                // Use the Anti-XSRF token from the cookie
                _antiXsrfTokenValue = requestCookie.Value;
                Page.ViewStateUserKey = _antiXsrfTokenValue;
            }
            else
            {
                // Generate a new Anti-XSRF token and save to the cookie
                _antiXsrfTokenValue = Guid.NewGuid().ToString("N");
                Page.ViewStateUserKey = _antiXsrfTokenValue;

                var responseCookie = new HttpCookie(AntiXsrfTokenKey)
                {
                    HttpOnly = true,
                    Value = _antiXsrfTokenValue
                };
                if (FormsAuthentication.RequireSSL && Request.IsSecureConnection)
                {
                    responseCookie.Secure = true;
                }
                Response.Cookies.Set(responseCookie);
            }

            Page.PreLoad += master_Page_PreLoad;
        }

        protected void master_Page_PreLoad(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                // Set Anti-XSRF token
                ViewState[AntiXsrfTokenKey] = Page.ViewStateUserKey;
                ViewState[AntiXsrfUserNameKey] = Context.User.Identity.Name ?? String.Empty;
            }
            else
            {
                // Validate the Anti-XSRF token
                if ((string)ViewState[AntiXsrfTokenKey] != _antiXsrfTokenValue
                    || (string)ViewState[AntiXsrfUserNameKey] != (Context.User.Identity.Name ?? String.Empty))
                {
                    throw new InvalidOperationException("Validation of Anti-XSRF token failed.");
                }
            }
        }

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack)
            {
                if (Session["Agent"] == null)
                {
                    lblLogOut.Text = "Logged Out";
                    HyperLink logIn = new HyperLink();
                    logIn.Text = "Log In";
                    logIn.NavigateUrl = "~/Default.aspx";
                    lblLogin.Controls.Add(logIn);

                    Response.Redirect("~/Default.aspx", false);
                }
                else
                {
                    Agent _user = new Agent();
                    _user = (Agent)Session["Agent"];
                    lblLogin.Text = "Logged in as: " + _user.UserName;
                    HyperLink logOut = new HyperLink();
                    logOut.Text = "Log Out";
                    logOut.NavigateUrl = "~/Logout.aspx";
                    lblLogOut.Controls.Add(logOut);

                    if (_user.UserName != "support")
                    {
                        Response.Redirect("~/Default.aspx", false);
                    }
                }
            }
        }
    }