How to protect against CSRF when using Backbone.js to post data?

Question

Backbone.js handles posting data to server under the hood, so there is no easy way to insert a CSRF token in the payload. How can I protect my site against CSRF in this situatio

Answer 1

Here's an updated version, based in Django 1.7 (using the jQuery cookie plugin)

oldSync = Backbone.sync
Backbone.sync = (method, model, options) ->

    csrfSafeMethod = (method) ->
        # these HTTP methods do not require CSRF protection
        /^(GET|HEAD|OPTIONS|TRACE)$/.test method

    options.beforeSend = (xhr, settings) ->
        if !csrfSafeMethod(settings.type) and !@crossDomain
            xhr.setRequestHeader 'X-CSRFToken', $.cookie('csrftoken')
        return
    oldSync method, model, options

Answer 2

You can use a prefilter to add the token to all requests:

$.ajaxPrefilter(function(opts) {
    if (opts.data) {
        opts.data += "&";
    }
    opts.data += "csrfToken=" + token;
});

You may need to add additional logic if you don't always send the token.

Answer 3

I know it's a bit old question, but I'll leave a link to the github repo of AMD module just for this:

https://github.com/kuc2477/backbone.csrf.git (disclaimer: I'm the author of the module)

Answer 4

Setting a global CSRF-token for all jQuery.ajax calls:

$(function(){ 
  $.ajaxSetup({
    headers: {'X-CSRFToken': CSRF_TOKEN}
  });
})

Setting the token just for Backbone by overriding Backbone.sync:

var oldSync = Backbone.sync;
Backbone.sync = function(method, model, options){
  options.beforeSend = function(xhr){
    xhr.setRequestHeader('X-CSRFToken', CSRF_TOKEN);
  };
  return oldSync(method, model, options);
};

EDIT: Fixed a typo Kadam points at in comments