Ask Slashdot: Has Gmail's SSL Certificate Changed, How Would We Know?

An anonymous reader writes "Recent reports from around the net suggest that SSL certificate chain for gmail has either changed this week, or has been widely compromised. Even less-than-obvious places to look for information, such as Google's Online Security Blog, are silent. The problem isn't specific to gmail, of course, which leads me to ask: What is the canonically-accepted out-of-band means by which a new SSL certificate's fingerprint may be communicated and/or verified by end users?"

Comments

Google announced this

[supersat]

Back in May, Google announced that they would be making changes to their SSL/TLS certificates in the coming months: http://googleonlinesecurity.blogspot.com/2013/05/changes-to-our-ssl-certificates.html

If you use Chrome, Google's SSL certificates are pinned, so that gives you some additional assurance.

Re:Google announced this

[Trax3001BBS]

Back in May, Google announced that they would be making changes to their SSL/TLS certificates in the coming months: http://googleonlinesecurity.blogspot.com/2013/05/changes-to-our-ssl-certificates.html

Oh No's!
"Even in less-than-obvious places to look for information, such as Google's Online Security Blog, are silent."

To a non-story
"Back in May, Google announced..."

Thanks for that.

Why do we trust SSL?

[JWSmythe]

    That made me wonder about something at work recently. All the machines at work are owned by the organization. It would be trivial for them to add their own trusted signing authority, so they could MITM every SSL web site. It wouldn't be terribly hard to auto-generate "valid" SSL certs, and have it tagged as whoever you want the signing authority to be. All they'd have to do is add their own cert, in this case named "GeoTrust Global CA", and they'd have perfect control. To do it perfectly, they'd just need to query the site you're going to, and match up the signer's CN and sign the new fake cert, and you wouldn't know the difference. Who tracks the fingerprint of every cert for every site they go to? Well, I'm sure in this crowd, a few do.

    It's good for network security, as they can pump everything out through a common proxy (or cluster of proxies) and inspect all the traffic for malicious intent (malware inbound, or organization secrets outbound). It's not good for privacy, if you were to visit your bank, gmail, etc.

    As far as that goes, there are an awful lot of "trusted" signing authorities that come with any browser. I know we should probably trust them, because the authors of the browsers trust them. There's no really good reason to do so, other than if you don't, all SSL sites will warn that they may not be trustworthy.

    I was considering a while back, how would *I* become my own signing authority, to be trusted by all browsers. I didn't find a good answer. An intermediary cert would solve it, but I didn't find how to accomplish that. Like, who do I throw money at to get one. Getting added to all browsers would be another even larger headache.

    My thought on it was, technically it isn't hard to do. I could spend a day writing a very nice site, that would verify ownership and make whatever cert for the domain. Why can't I (or whoever) offer $5/yr, or $50/10yr single domain or wildcard cert? The code and infrastructure isn't very heavy.

    Needless to say, since you haven't seen JWSmythe's Cheap Certs available, it never happened.

Re:Why do we trust SSL?

[forkazoo]

That made me wonder about something at work recently. All the machines at work are owned by the organization. It would be trivial for them to add their own trusted signing authority, so they could MITM every SSL web site. It wouldn't be terribly hard to auto-generate "valid" SSL certs, and have it tagged as whoever you want the signing authority to be. All they'd have to do is add their own cert, in this case named "GeoTrust Global CA", and they'd have perfect control. To do it perfectly, they'd just need to query the site you're going to, and match up the signer's CN and sign the new fake cert, and you wouldn't know the difference. Who tracks the fingerprint of every cert for every site they go to? Well, I'm sure in this crowd, a few do.

It's not merely possible. It's deployed, off the shelf technology. Not necessarily common, but many companies that do it see it as a cost reduction of more effective proxy usage, rather than anything nefarious.

That said, the way SSL is handled by the browsers is absurd. Not notifying on changes compared to a cached fingerprint, and giving huge warnings on self certification are blatantly obvious errors in judgement. Conflating encryption and identity in one awkward mess has probably done more harm than good. IMHO, it should work a bit like SSH, where the first time you go to a website, you see a little unobtrusive popup saying, "This connection is encrypted. The site claims to be "Foo corp." The identity is (not verified || vouched for by the following : CA Bar, CA Baz). " Adding certs for CA's should be really obvious, not obscure black magic. So, if you attend University of Foo, you can add their self signed cert and all the servers on campus that you access over https will show up as signed by U of Foo. Untrusting certs should also be obvious in the UI. Some web of trust model should be available. If you ever get something other than what was cached, you should see the details side by side.

As is, the system is mostly useless. It fails utterly at identification. And, it scares people away from using encryption on self signed certs. (As if that were somehow worse than operating entirely in plain text...)

Re:Why do we trust SSL?

[VortexCortex]

That said, the way SSL is handled by the browsers is absurd. Not notifying on changes compared to a cached fingerprint, and giving huge warnings on self certification are blatantly obvious errors in judgement. Conflating encryption and identity in one awkward mess has probably done more harm than good. IMHO, it should work a bit like SSH, where the first time you go to a website, you see a little unobtrusive popup saying, "This connection is encrypted.

Yep, completely absurd. Go into your browser security certs and notice that the Chinese root cert "CNNIC" is installed. That means any of those trusted roots can simply create an SSL cert for Google.com and unless you're manually verifying the cert chain every time you connect, you won't know you've been MITM'd -- Big green bar and everything... I like your idea about making things more like SSH, but I'm afraid users will just click through it without reading any warnings anyway. Oh, if only PKI hadn't been invented! Why, then we could just use some session salt nonce HMAC'd with our pre-shared key (password) to set up a connection that no man in the middle can intercept (since they don't have our password, or password hash, etc pre-shared secret). I can do this in JavaScript, (or more favorably with a plugin), but we really need the browsers to just prompt us for the credential to our bank or email BEFORE it ever makes the request or displays the password entry form -- The request comes in, says : "I'm user X, here's my nonce, gimme your nonce server, and we can start encrypting data with HMAC( PW, N1 ) as the key". Public key crypto should have only ever been used at account creation (the only time you need to send the pre-shared secret). I've always known the entire security community was full of morons since they didn't bitch about the foolishness of SSL PKI loudly enough -- Oh, and for the "but muh passwerds!" folks: Built in password manager. Different random password for every site, master password to unlock the keystore. This is 2013 and since it's not standard addition to browsers, I'm not sure folks like you or me CAN do anything about it if we haven't already.

Additionally: People who searched for "Tinfoil Origami" also clicked on Convergence.

Detecting Certificate Change

[seawall]

Addons for web browsers (e,g. Certificate Patrol in Firefox, there are others) can clue you into certificate changes. Rather like Ghostery (which shows where stuff is loading from in a web page): it is an eye opener.

Certificate Transparency

[goddidit]

Certificate transparency is a new project initiated at least partly by Google's engineers, which intends to solve this problem with SSL trust model: http://www.certificate-transparency.org/
It uses an append only public log, similar to Bitcoin transaction log to make certificate information public.

Revocation --- or Redundancy?

[ron_ivi]

I wonder why HTTPS stuff can't require *two* certificates that validate. That way unless both CAs are compromised, the traffic's safe.

It's just like any other single-point-of-failure in your network. You probably work with two telcom companies to make sure your website and/or company has network access. Why shouldn't you do the same for certificates. Buy one from a US CA, one from a Russian one, and one from a Chinese one, and if browsers could check to make sure *all* (or two out of the three, whatever) validate, unless they collude you should be pretty safe.

Even better if one of those can be a self-signed one. You can even exchange those keys over normal boring https, and then unless your commercial CA was already hacked at the time you distribute your self-signed one, your self-signed one will protect against your commercial CA being hacked in the future.

Re:Revocation --- or Redundancy?

[petermgreen]

Do you even know how PKI works?

Currently PKI works by having a large number of certification authorities (both roots installed in the browser and intermediates with delegated authority from those roots) any one of which can issue a certificate that will be trusted by the browser to identify a site. So if any one of those certification authorities is compromised by an attacker then the attacker can obtain a certificate with which they can MITM traffic to your site without generating any warnings.

AIUI What the GP is proposing is that multiple independent authorities would need to vouch for a "high security" site so that one compromised certification authority would not be sufficiant to perform a man in the middle attack. It's a nice idea in principle but there are several practical issues to deal with.

1: How do you define independent authority. I'm sure there are cases where multiple root certificates are controlled by the same entity.
2: How do you decide what sites it should apply to. One possibility would be to never allow the number of authorities for a site to go down so once a site had been seen with more than 1
3: How do we modify the protocols to support this.
4: How do we convince site operators to adopt this.