Jquery Ajax 调用和 Html.AntiForgeryToken ()

I have implemented in my app the mitigation to CSRF attacks following the informations that I have read on some blog post around the internet. In particular these post have been the driver of my implementation

Basically those articles and recommendations says that to prevent the CSRF attack anybody should implement the following code:

1) Add the [ValidateAntiForgeryToken] on every action that accept the POST Http verb

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult SomeAction( SomeModel model ) {
}

2) Add the <%= Html.AntiForgeryToken() %> helper inside forms that submits data to the server

<div style="text-align:right; padding: 8px;">
    <%= Html.AntiForgeryToken() %>
    <input type="submit" id="btnSave" value="Save" />
</div>

Anyway in some parts of my app I am doing Ajax POSTs with jQuery to the server without having any form at all. This happens for example where I am letting the user to click on an image to do a specific action.

Suppose I have a table with a list of activities. I have an image on a column of the table that says "Mark activity as completed" and when the user click on that activity I am doing the Ajax POST as in the following sample:

$("a.markAsDone").click(function (event) {
    event.preventDefault();
    $.ajax({
        type: "post",
        dataType: "html",
        url: $(this).attr("rel"),
        data: {},
        success: function (response) {
            // ....
        }
    });
});

How can I use the <%= Html.AntiForgeryToken() %> in these cases? Should I include the helper call inside the data parameter of the Ajax call?

Sorry for the long post and thanks very much for helping out

EDIT:

As per jayrdub answer I have used in the following way

$("a.markAsDone").click(function (event) {
    event.preventDefault();
    $.ajax({
        type: "post",
        dataType: "html",
        url: $(this).attr("rel"),
        data: {
            AddAntiForgeryToken({}),
            id: parseInt($(this).attr("title"))
        },
        success: function (response) {
            // ....
        }
    });
});

转载于:https://stackoverflow.com/questions/4074199/jquery-ajax-calls-and-the-html-antiforgerytoken

csdnceshi57
perhaps? The David Hayden link now 404s, it appears that he's migrated his blog to a new CMS, but didn't migrate all the old content over.
7 年多之前 回复

16个回答

I was just implementing this actual problem in my current project. i did it for all ajax-POSTs that needed an authenticated user.

First off i decided to hook my jquery ajax calls so i do not to repeat myself too often. this javascript snippet ensures all ajax (post) calls will add my request validation token to the request. Note: the name __RequestVerificationToken is used by the .Net framework so i can utilize the standard Anti-CSRF features as shown below.

$(document).ready(function () {
    var securityToken = $('[name=__RequestVerificationToken]').val();
    $('body').bind('ajaxSend', function (elm, xhr, s) {
        if (s.type == 'POST' && typeof securityToken != 'undefined') {
            if (s.data.length > 0) {
                s.data += "&__RequestVerificationToken=" + encodeURIComponent(securityToken);
            }
            else {
                s.data = "__RequestVerificationToken=" + encodeURIComponent(securityToken);
            }
        }
    });
});

In your Views where you need the token to be available to the above javascript just use the common HTML-Helper. You can basically add this code whereever you want. I placed it within a if(Request.IsAuthenticated) statement:

@Html.AntiForgeryToken() // you can provide a string as salt when needed which needs to match the one on the controller

In your controller simply use the standard ASP.Net MVC Anti-CSRF mechanism. I did it like this (though i actually used Salt).

[HttpPost]
[Authorize]
[ValidateAntiForgeryToken]
public JsonResult SomeMethod(string param)
{
    // do something
    return Json(true);
}

With Firebug or a similar tool you can easily see how your POST requests now have a __RequestVerificationToken parameter appended.

csdnceshi80
胖鸭 good solution. thx.
大约 8 年之前 回复

You can do this also:

$("a.markAsDone").click(function (event) {
    event.preventDefault();

    $.ajax({
        type: "post",
        dataType: "html",
        url: $(this).attr("rel"),
        data: $('<form>@Html.AntiForgeryToken()</form>').serialize(),
        success: function (response) {
        // ....
        }
    });
});

This is using Razor, but if you're using WebForms syntax you can just as well use <%= %> tags

I know there are a lot of other answers, but this article is nice and concise and forces you to check all of your HttpPosts, not just some of them:

http://richiban.wordpress.com/2013/02/06/validating-net-mvc-4-anti-forgery-tokens-in-ajax-requests/

It uses HTTP headers instead of trying to modify the form collection.

Server

//make sure to add this to your global action filters
[AttributeUsage(AttributeTargets.Class)]
public class ValidateAntiForgeryTokenOnAllPosts : AuthorizeAttribute
{
    public override void OnAuthorization( AuthorizationContext filterContext )
    {
        var request = filterContext.HttpContext.Request;

        //  Only validate POSTs
        if (request.HttpMethod == WebRequestMethods.Http.Post)
        {
            //  Ajax POSTs and normal form posts have to be treated differently when it comes
            //  to validating the AntiForgeryToken
            if (request.IsAjaxRequest())
            {
                var antiForgeryCookie = request.Cookies[AntiForgeryConfig.CookieName];

                var cookieValue = antiForgeryCookie != null
                    ? antiForgeryCookie.Value 
                    : null;

                AntiForgery.Validate(cookieValue, request.Headers["__RequestVerificationToken"]);
            }
            else
            {
                new ValidateAntiForgeryTokenAttribute()
                    .OnAuthorization(filterContext);
            }
        }
    }
}

Client

var token = $('[name=__RequestVerificationToken]').val();
var headers = {};
headers["__RequestVerificationToken"] = token;

$.ajax({
    type: 'POST',
    url: '/Home/Ajax',
    cache: false,
    headers: headers,
    contentType: 'application/json; charset=utf-8',
    data: { title: "This is my title", contents: "These are my contents" },
    success: function () {
        ...
    },
    error: function () {
        ...
    }
});
csdnceshi62
csdnceshi62 thanks Tim, it is an excellent idea, its frustrating when a link goes dead and the answer becomes worthless. I've started doing this on all my new answers.
大约 6 年之前 回复
weixin_41568174
from.. Great find. I edited your answer to include the code snippets so the answer stands on its own, but I hope people will read the rest of the article as well. This appears to be a very clean solution.
6 年多之前 回复
csdnceshi73
喵-见缝插针 The attribute from the article you linked too combined with Bronx's response is the ultimate DRY solution to this problem.
6 年多之前 回复

I like the solution provided by 360Airwalk, but it may be improved a bit.

The first problem is that if you make $.post() with empty data, jQuery doesn't add a Content-Type header, and in this case ASP.NET MVC fails to receive and check the token. So you have to ensure the header is always there.

Another improvement is support of all HTTP verbs with content: POST, PUT, DELETE etc. Though you may use only POSTs in your application, it's better to have a generic solution and verify that all data you receive with any verb has an anti-forgery token.

$(document).ready(function () {
    var securityToken = $('[name=__RequestVerificationToken]').val();
    $(document).ajaxSend(function (event, request, opt) {
        if (opt.hasContent && securityToken) {   // handle all verbs with content
            var tokenParam = "__RequestVerificationToken=" + encodeURIComponent(securityToken);
            opt.data = opt.data ? [opt.data, tokenParam].join("&") : tokenParam;
            // ensure Content-Type header is present!
            if (opt.contentType !== false || event.contentType) {
                request.setRequestHeader( "Content-Type", opt.contentType);
            }
        }
    });
});
weixin_41568131
10.24 Beware using this if you have multiple forms on a page. You will need to set the value in beforeSend with a more specific selector call instead of for the document.
大约 4 年之前 回复
weixin_41568110
七度&光 good catch, thank you. Fixed.
4 年多之前 回复
csdnceshi80
胖鸭 Where does the options come from, which is listed in the final if statement? Thanks.
4 年多之前 回复
weixin_41568110
七度&光 Thank you, @RJCuthbertson, I modified the code.
大约 6 年之前 回复
weixin_41568184
叼花硬汉 +1 Just as a note for posterity, the jQuery documentation for .ajaxSend() states "As of jQuery 1.8, the .ajaxSend() method should only be attached to document." api.jquery.com/ajaxsend
大约 6 年之前 回复
csdnceshi76
斗士狗 +1 for saving me from having to add the function to all the jQuery.Ajax calls
接近 8 年之前 回复
csdnceshi75
衫裤跑路 +1 you are right, i've not thought of the empty post call issue. thanks for the input. you were right about that we do not use delete/put yet in our project.
大约 8 年之前 回复

I feel like an advanced necromancer here, but this is still an issue 4 years later in MVC5.

To handle ajax requests properly the anti-forgery token needs to be passed to the server on ajax calls. Integrating it into your post data and models is messy and unnecessary. Adding the token as a custom header is clean and reusable - and you can configure it so you don't have to remember to do it every time.

There is an exception - Unobtrusive ajax does not need special treatment for ajax calls. The token is passed as usual in the regular hidden input field. Exactly the same as a regular POST.

_Layout.cshtml

In _layout.cshtml I have this JavaScript block. It doesn't write the token into the DOM, rather it uses jQuery to extract it from the hidden input literal that the MVC Helper generates. The Magic string that is the header name is defined as a constant in the attribute class.

<script type="text/javascript">
    $(document).ready(function () {
        var isAbsoluteURI = new RegExp('^(?:[a-z]+:)?//', 'i');
        //http://stackoverflow.com/questions/10687099/how-to-test-if-a-url-string-is-absolute-or-relative

        $.ajaxSetup({
            beforeSend: function (xhr) {
                if (!isAbsoluteURI.test(this.url)) {
                    //only add header to relative URLs
                    xhr.setRequestHeader(
                       '@.ValidateAntiForgeryTokenOnAllPosts.HTTP_HEADER_NAME', 
                       $('@Html.AntiForgeryToken()').val()
                    );
                }
            }
        });
    });
</script>

Note the use of single quotes in the beforeSend function - the input element that is rendered uses double quotes that would break the JavaScript literal.

Client JavaScript

When this executes the beforeSend function above is called and the AntiForgeryToken is automatically added to the request headers.

$.ajax({
  type: "POST",
  url: "CSRFProtectedMethod",
  dataType: "json",
  contentType: "application/json; charset=utf-8",
  success: function (data) {
    //victory
  }
});

Server Library

A custom attribute is required to process the non standard token. This builds on @viggity's solution, but handles unobtrusive ajax correctly. This code can be tucked away in your common library

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
public class ValidateAntiForgeryTokenOnAllPosts : AuthorizeAttribute
{
    public const string HTTP_HEADER_NAME = "x-RequestVerificationToken";

    public override void OnAuthorization(AuthorizationContext filterContext)
    {
        var request = filterContext.HttpContext.Request;

        //  Only validate POSTs
        if (request.HttpMethod == WebRequestMethods.Http.Post)
        {

            var headerTokenValue = request.Headers[HTTP_HEADER_NAME];

            // Ajax POSTs using jquery have a header set that defines the token.
            // However using unobtrusive ajax the token is still submitted normally in the form.
            // if the header is present then use it, else fall back to processing the form like normal
            if (headerTokenValue != null)
            {
                var antiForgeryCookie = request.Cookies[AntiForgeryConfig.CookieName];

                var cookieValue = antiForgeryCookie != null
                    ? antiForgeryCookie.Value
                    : null;

                AntiForgery.Validate(cookieValue, headerTokenValue);
            }
            else
            {
                new ValidateAntiForgeryTokenAttribute()
                    .OnAuthorization(filterContext);
            }
        }
    }
}

Server / Controller

Now you just apply the attribute to your Action. Even better you can apply the attribute to your controller and all requests will be validated.

[HttpPost]
[ValidateAntiForgeryTokenOnAllPosts]
public virtual ActionResult CSRFProtectedMethod()
{
  return Json(true, JsonRequestBehavior.DenyGet);
}
weixin_41568183
零零乙 Does anyone have an ASP.net 5 version of the customer validate AntiForgery attribute? This version does not compile in the latest version!
4 年多之前 回复
csdnceshi55
~Onlooker I liked your solution, but was forced to modify it a bit. Because you choose $.ajaxSetup to define a general beforesend eventhandler it can happen that you overwrite it. I found another solution where you can add a second handler which will also be called. Works nicely and doesn't break your implementation.
接近 5 年之前 回复
weixin_41568127
?yb? relative ensures that the header is only set on requests going back to your own server, as the ajax setup covers all requests made with jquery, we don't want the token being sent on jsonp or CORS requets. This maybe true for absolute urls too, but relative are guaranteed to be same domain.
大约 5 年之前 回复
csdnceshi67
bug^君 Can you explain in more detail why you only want to add the header for relative URLs? That went over my head. Great solution!
大约 5 年之前 回复
weixin_41568184
叼花硬汉 Perfect solution, much more centralized. Thanks
5 年多之前 回复

Further to my comment against @JBall's answer that helped me along the way, this is the final answer that works for me. I'm using MVC and Razor and I'm submitting a form using jQuery AJAX so I can update a partial view with some new results and I didn't want to do a complete postback (and page flicker).

Add the @Html.AntiForgeryToken() inside the form as usual.

My AJAX submission button code (i.e. an onclick event) is:

//User clicks the SUBMIT button
$("#btnSubmit").click(function (event) {

//prevent this button submitting the form as we will do that via AJAX
event.preventDefault();

//Validate the form first
if (!$('#searchForm').validate().form()) {
    alert("Please correct the errors");
    return false;
}

//Get the entire form's data - including the antiforgerytoken
var allFormData = $("#searchForm").serialize();

// The actual POST can now take place with a validated form
$.ajax({
    type: "POST",
    async: false,
    url: "/Home/SearchAjax",
    data: allFormData,
    dataType: "html",
    success: function (data) {
        $('#gridView').html(data);
        $('#TestGrid').jqGrid('setGridParam', { url: '@Url.Action("GetDetails", "Home", Model)', datatype: "json", page: 1 }).trigger('reloadGrid');
    }
});

I've left the "success" action in as it shows how the partial view is being updated that contains an MvcJqGrid and how it's being refreshed (very powerful jqGrid grid and this is a brilliant MVC wrapper for it).

My controller method looks like this:

    //Ajax SUBMIT method
    [ValidateAntiForgeryToken]
    public ActionResult SearchAjax(EstateOutlet_D model) 
    {
        return View("_Grid", model);
    }

I have to admit to not being a fan of POSTing an entire form's data as a Model but if you need to do it then this is one way that works. MVC just makes the data binding too easy so rather than subitting 16 individual values (or a weakly-typed FormCollection) this is OK, I guess. If you know better please let me know as I want to produce robust MVC C# code.

found this very clever idea from https://gist.github.com/scottrippey/3428114 for every $.ajax calls it modifies the request and add the token.

// Setup CSRF safety for AJAX:
$.ajaxPrefilter(function(options, originalOptions, jqXHR) {
    if (options.type.toUpperCase() === "POST") {
        // We need to add the verificationToken to all POSTs
        var token = $("input[name^=__RequestVerificationToken]").first();
        if (!token.length) return;

        var tokenName = token.attr("name");

        // If the data is JSON, then we need to put the token in the QueryString:
        if (options.contentType.indexOf('application/json') === 0) {
            // Add the token to the URL, because we can't add it to the JSON data:
            options.url += ((options.url.indexOf("?") === -1) ? "?" : "&") + token.serialize();
        } else if (typeof options.data === 'string' && options.data.indexOf(tokenName) === -1) {
            // Append to the data string:
            options.data += (options.data ? "&" : "") + token.serialize();
        }
    }
});

Don't use Html.AntiForgeryToken. Instead, use AntiForgery.GetTokens and AntiForgery.Validate from Web API as described in Preventing Cross-Site Request Forgery (CSRF) Attacks.

csdnceshi68
local-host It certainly does not require a form. You just need to parse the DOM for it by name. Using jquery, I can add it inside my data object via data { __RequestVerificationToken: $("input[name=__RequestVerificationToken]").val() }
4 年多之前 回复
csdnceshi72
谁还没个明天 thx! I had to change it a bit to make it work for an MVC5 controller, but this was the solution
大约 6 年之前 回复
csdnceshi77
狐狸.fox There's nothing inherently wrong with Html.AntiForgeryToken, but it has downsides: requires a form, requires jQuery, and assumes undocumented Html.AntiForgeryToken implementation details. Still, it's fine in many contexts. My statement "Don't use Html.AntiForgeryToken" probably comes off too strong. My meaning is that it's not intended to be used with Web API, whereas the more flexible AntiForgery.GetTokens is.
6 年多之前 回复
weixin_41568184
叼花硬汉 Brey Can you please elaborate on why we shouldn't use it?
6 年多之前 回复
csdnceshi66
必承其重 | 欲带皇冠 For controller action methods that model bind a server model type to the posted AJAX JSON, having the content type as "application/json" is required for the proper model binder to be used. Unfortunately, this precludes using form data, required by the [ValidateAntiForgeryToken] attribute, so your method is the only way I could find to make it work. My only question is, does it still work in a web farm or multiple Azure web role instances? Do you @Edward, or anyone else know if this is a problem?
7 年多之前 回复

1.Define Function to get Token from server

@function
{

        public string TokenHeaderValue()
        {
            string cookieToken, formToken;
            AntiForgery.GetTokens(null, out cookieToken, out formToken);
            return cookieToken + ":" + formToken;                
        }
}

2.Get token and set header before send to server

var token = '@TokenHeaderValue()';    

       $http({
           method: "POST",
           url: './MainBackend/MessageDelete',
           data: dataSend,
           headers: {
               'RequestVerificationToken': token
           }
       }).success(function (data) {
           alert(data)
       });

3. Onserver Validation on HttpRequestBase on method you handle Post/get

        string cookieToken = "";
        string formToken = "";
        string[] tokens = Request.Headers["RequestVerificationToken"].Split(':');
            if (tokens.Length == 2)
            {
                cookieToken = tokens[0].Trim();
                formToken = tokens[1].Trim();
            }
        AntiForgery.Validate(cookieToken, formToken);

I aware it's been some time since this question was posted, but I found really useful resource, which discusses usage of AntiForgeryToken and makes it less troublesome to use. It also provides jquery plugin for easily including antiforgery token in AJAX calls:

Anti-Forgery Request Recipes For ASP.NET MVC And AJAX

I'm not contributing much, but maybe someone will find it useful.

csdnceshi62
csdnceshi62 If it's important it should be written in a way that encourages people to read it ;)
8 年多之前 回复
weixin_41568183
零零乙 Too bad, because it nicely covers subject. It not only tells you how to use the feature, but explains what problem it fixes and give you context to understand how to use it correctly. When it comes to security I think in-depth understanding is important.
8 年多之前 回复
csdnceshi62
csdnceshi62 That post is like a mile long! I'm sure it's great but tl;dr
8 年多之前 回复
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