Thursday, August 26, 2010

HTTP Strict Transport Security has landed!

It was a year ago now that I first blogged about ForceTLS, and it's matured quite a bit since. I revised ForceTLS to be more robust, and began actually implementing it as HTTP-Strict-Transport-Security in Firefox. I'm excited to say that my patch has been reviewed and landed in mozilla-central.

What's that mean? Look for it in the next beta release of Firefox 4! If you can't wait, grab a nightly build, but when 4.0 is released, HTTP Strict-Transport-Security will be built-in and turned on by default.

Though the feature's core functionality is there, work on HSTS is not completely finished. There are still a few tweaks I'd like to make, mainly providing a decent UI so people can add/remove HSTS state for servers themselves -- but none of this is necessary to be specification compliant. As landed, HSTS is the behind-the-scenes implementation that listens to the HTTP Strict-Transport-Security header and follows those instructions.

In case you don't feel like trawling through the IETF Internet Draft specification but you want to figure out how it works, here's a quick summary:

  1. Over an HTTPS connection, the server provides the Strict-Transport-Security header indicating it wants to be an HSTS host. It looks something like this:
    Strict-Transport-Security: max-age=60000
    The header's presence indicates the server's desire to be an HSTS host, and the max-age states for how many seconds the browser should remember this.
  2. For an HSTS host (e.g.,, any subsequent requests assembled for an insecure connection to that host (, will be rewritten to a secure request ( before any network connection is opened.
  3. Optionally, the header can include a second includeSubdomains directive that tells the browser to additionally "upgrade" all subdomains of the serving host. That looks like this:
    Strict-Transport-Security: max-age=60000; includeSubdomains

If Firefox knows your host is an HSTS one, it will automatically establish a secure connection to your server without even trying an insecure one. This way, if I am surfing the 'net in my favorite cafe and a hacker is playing MITM with (intercepting http requests for and then forwarding them on to the real site), either I'll thwart the attacker by getting an encrypted connection to immediately, or the attack will be detected by HSTS and the connection won't work at all.

There are more details in the specification, like some further restrictions on cert errors and the like, but this is the general setup, and I believe a pretty nice feature to increase your site's security.

Also: Jeff and Andy at Paypal are working hard at standardizing this.

Thursday, August 19, 2010

facebook again


I was gonna blog about this new Facebook data collection feature, but why rehash a the same thoughts? From Michael Coates:

"The last thing to consider is facebook's track record on protecting data. How long will it be until advertisers find a way to pilfer this data from people? Or what about the next privacy setting overhaul which changes the defaults or makes it more difficult to control who sees your location data?"

And the vicious cycle begins again. I don't agree that it's all about advertisers (I'm an optimist here), but the wash-rinse-repeat cycle gets tiresome: (1) add new data collection feature (2) public outrage (3) respin privacy settings (4) repeat.

Tuesday, August 17, 2010


Michael Coates writes:
Several Mozilla employees will be attending this year's OWASP AppSecUSA event held in Irvine, CA (Sept 7-10). OWASP conferences focuse entirely on application security and are considered the premier event for this area of security.
I'm one of those mysterious Mozilla folk going to the meeting, and if you're there drop by and say hi. If you're not, you should consider coming! OWASP does wonderful things for web application security, and there are always fantastic talks to look forward to at AppSec USA.

This year, I'm hoping to spread the word about Content Security Policy a bit more; if you run a web site (or better yet, if you secure one) come find us at our booth or harass one of the Mozilla folk in the hallway and we'll be more than happy to help figure out how CSP can make your site more secure for your users.