Это старый вопрос, но последний шаблон Visual Studio 2012 ASP.NET для веб-форм включает анти-CSRF-код, запеченный на главной странице. Если у вас нет шаблонов, вот код, который он генерирует:
Protected Sub Page_Init(sender As Object, e As System.EventArgs)
' The code below helps to protect against XSRF attacks
Dim requestCookie As HttpCookie = Request.Cookies(AntiXsrfTokenKey)
Dim requestCookieGuidValue As Guid
If ((Not requestCookie Is Nothing) AndAlso Guid.TryParse(requestCookie.Value, requestCookieGuidValue)) Then
' 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
Dim responseCookie As HttpCookie = New HttpCookie(AntiXsrfTokenKey) With {.HttpOnly = True, .Value = _antiXsrfTokenValue}
If (FormsAuthentication.RequireSSL And Request.IsSecureConnection) Then
responseCookie.Secure = True
End If
Response.Cookies.Set(responseCookie)
End If
AddHandler Page.PreLoad, AddressOf master_Page_PreLoad
End Sub
Private Sub master_Page_PreLoad(sender As Object, e As System.EventArgs)
If (Not IsPostBack) Then
' Set Anti-XSRF token
ViewState(AntiXsrfTokenKey) = Page.ViewStateUserKey
ViewState(AntiXsrfUserNameKey) = If(Context.User.Identity.Name, String.Empty)
Else
' Validate the Anti-XSRF token
If (Not DirectCast(ViewState(AntiXsrfTokenKey), String) = _antiXsrfTokenValue _
Or Not DirectCast(ViewState(AntiXsrfUserNameKey), String) = If(Context.User.Identity.Name, String.Empty)) Then
Throw New InvalidOperationException("Validation of Anti-XSRF token failed.")
End If
End If
End Sub