I spoke about CSRF attacks at Defcon a few months ago, and while I was there, I had the opportunity to meet with Justin Samuel, the creator of RequestPolicy. RequestPolicy is a Firefox extension designed to provide CSRF protection and enforce web application boundaries. I love it.

Request Policy completely breaks the web... in all the right ways. You'll initially hate using it. StumbleUpon links will no longer work, due to their use of cross-site iframes. Shortened bit.ly and tinyurl links will present you with an intermediate page instead of following 302 redirects. Deeplinked images on blogs, social networking sites, and other pages won't show up. You will have to manually approve off-domain requests on a case-by-case basis. It's not convenient, but it's a lot safer than letting your browser blindly request resources.

In short, RequestPolicy gives you granular control over your browser. If you know what you're doing, this is a good thing. If you're a normal user, you'll probably find yourself checking the "Temporarily Allow All Requests" box or disabling the extension completely. I can't say I'd blame you, but try not to. The extension is still very young in its development process, and most of the issues that I've run into are UI/usability problems. The developer is aware of many of these issues and working to fix them, but it's not easy. Samuel is very open to suggestions, feedback, and criticism, so if you have useful input, I'm sure he'd be happy to hear it- just hit the contact link on the extension's website.

The UI is heavily modeled after NoScript, so if you're a fan of that extension (and you should be), it isn't too difficult to figure out. Off-domain requests are disabled by default, and can be enabled on a per-site, as-needed basis. The preferences pane is simple and fairly easy to understand, allowing you to more easily manage your whitelist of allowed domains. Additionally, the extension ships with a setup wizard to create generic whitelists based on common sites (recaptcha, for example, has to be whitelisted for every domain that uses it). All in all, it's pretty easy to set up, and though it will break a lot of sites at first, as you fine tune the settings to your browsing habits, it really doesn't get in the way too much.

RequestPolicy was created for a very specific purpose: to give users the ability to better control their browsers and prevent CSRF. It's a bit rough at the moment, but it's very good at it.

--Mike Bailey