This Green Bar Will Save Your Life!

Well … maybe not.

SSL: great idea; not always well executed. Certificate Authorities (CAs) that issue SSL certificates for websites are supposed to carefully vet the requester, to make sure the business is valid (lookup in D&B, for example), that the administrator actually works for the company in question (HR query), and that the DNS domain is owned by that enterprise. Once all these hoops are jumped through, the cert is issued.

It turns out, however, that it’s much easier and cheaper simply to check whether a given domain name is legitimate (for varying values of “legitimate”) and the person requesting a cert can receive email at that domain. This is what several CAs started to do for SSL—especially during price wars a half-decade ago—and is why https://phish-all-day.example.com could have its SSL cert despite nefarious intent.

Extended Validation (EV) certificates were supposed to solve this problem. By introducing a governance organization (the CA/Browser Forum http://www.cabforum.org/), creating new rules for vetting, refactoring Certificate Policies (CPs), and requiring stringent audits of CAs, EV-SSL-requesting businesses were supposed to receive special scrutiny to avoid fraud and mayhem in cert issuance. Furthermore, and importantly, browsers implement a candy-colored URL status bar 

to show users whether they’re browsing an EV-cert-equipped website or not (in truth, browser implementations to date are simply green or not-green specifically for EV-cert status; additional candy-coating is applied for reputation filters and other stuff). A side effect of this newfound rigor is more $$ charged for certificates.

Less fraud is a good thing, yes? Here’s the bad news: EV certs can be bypassed. As reported by The Register, “Websites that use an enhanced form of digital authentication remain just as vulnerable to a common form of spoofing attack.” www.theregister.co.uk/2009/03/28/ev_ssl_spoofing/) More than one person has stated that the green bar really doesn’t matter to users; it’s just a way for CAs to make more money. And although I believe in good intentions of the CA/Browser Forum, it seems that they went after the high-end revenue-generating solution and missed some essentials.

Comments

[jensentime]

I understand the appeal of knocking EV SSL certs, or security technology in general, and I applaud those who are forcing us to acknowledge just how vulnerable we really are. That having been said, however, the point of ANY kind of SSL has always been one thing, and one thing only -- to create a secure connection between two points (and ordinarily those points are exchanging some kind of private data). Can it be bypassed? Yes. Does that mean the secure connection is broken? No. It means that users are being diverted from the secure connection (ie, Man in the Middle attacks), and that requires a different sort of protection entirely separate from SSL (EV or otherwise).

I think it's funny how every attack on EV SSL from black hat folks so far has involved exploiting some other weakness in a website (for example, the CanSecWest DNS hit). Yes, mixed security level sites do present problems, but blaming SSL for them is like blaming Masterlock when a thief gets in through the back (unbolted) door.

I think SSL gets a lot of flack for this because it has a reputation for being THE security solution, even with people who don't know what the acronym stands for. But, again, getting EV SSL protection isn't like placing your website in a gleaming green tank. It simply provides more secure connections between a site and its customers, and the additional vetting process proves to customers that you are you who say you are. Beyond that we're in another area.

Oh, and when you say "More than one person has stated that the green bar really doesn’t matter to users; it’s just a way for CAs to make more money," do you just mean in the UK Register comments? Most of the data I've read has suggested the opposite (re: users noticing the difference and feeling safer), but browsers have been slow to adopt EV...

[Trent Henry]

@jensentime,

You are right to point out that we should distinguish between weaknesses in SSL itself and other attack vectors. It's really the whole browser ecosystem implicated here, not the SSL protocol or underlying crypto ciphers.

However, I'm reminded of an old adage: if you install a bank vault door at the front of a canvas tent, you don't get kudos for the strong door.

(By the way, I've gathered input from many users critical of EV certs--I used to be in the PKI industry myself. Just last week I had a conversation with a large enterprise IT manager who offered an unsolicited critique.)

[jensentime]

--However, I'm reminded of an old adage: if you install a bank vault door at the front of a canvas tent, you don't get kudos for the strong door.

True, true, and as I said, I think a lot of folks treat SSL like a solution to everything when truly it needs to be treated like one tool in the bag of e-security tricks. The browser ecosystem, as you eloquently put it, is a rather treacherous one, and both the problems and their solutions are more complex than most realize.

--(By the way, I've gathered input from many users critical of EV certs--I used to be in the PKI industry myself. Just last week I had a conversation with a large enterprise IT manager who offered an unsolicited critique.)

Very interesting! Thanks for clarifying that, as I've not heard the same critiques.

[Andy Steingruebl]

To be fair here, the recent CanSec talk didn't actually show getting a fake certificate for all sites. It isn't clear this is possible as not all sites allow a user to play the email verification trick.

There are some potential fixes such as a change to browsers to treat EV differently than standard SSL, but I don't think that really solves the problem.

Do you personally have suggestions for fixing this? One option is stricter standards for who is in the trusted-root list in a browser. Do you have other suggestions?