Become an SSLAdmin In a Few Easy Steps

Renderer of Evil writes "With news that it is rather simple to mimic authority with many webmail providers in order to coax an SSL certificate authority into creating one for the domain, a Canadian security expert has decided to take it upon himself to see who out there is actually vulnerable and provide information to the public on how prevalent this issue is as we speak. Out of eleven webmail services chosen at random and without prejudice, just under half of them permitted him to register with credentials (ssladmin) that allowed him to create an SSL certificate in their name. In most of these cases, there was a pre-existing, legitimately-acquired certificate." Update: 04/19 01:30 GMT by S : Kurt Seifried's original paper, on which the BetaNews article is based, provides more detailed information on the subject (PDF).

Comments

Re:Sometimes

[Arancaytar]

In a nutshell:

When you log in to your email account, the server sends you a certificate to confirm that it does indeed belong to the email provider and not an eavesdropper.

By registering an email account like "admin" or "ssladmin", an attacker could contact certification authorities and request a new certificate pretending to be a staff member of the service.

They could then use that certificate to intercept and redirect your connection to their own server, intercepting passwords and emails, while your browser will still tell you that you are connected with a genuine mail server.

Re:Sometimes

[Anonymous Coward]

He doesn't need to try this, it's established procedure. Yes, the idea behind SSL was to require more reliable identification than just being able to receive mail for one of a few mail addresses. What was initially the plan with SSL is now called an "extended verification" certificate. Regular SSL certificates are less secure than DNSSec distributed keys would be. DNSSec would at least ensure actual control over the domain, not just the ability to receive mail for that domain. The lack of proper authentication by the certificate authorities has been a problem for a long time and this is just another outrageously simple way of getting a certificate for someone else's domain.

Let me be clear on this: It's the CA's fault. The mail provider could plug this hole by not allowing users to register these addresses, but those addresses are arbitrary. It's the CA's job to ensure that they're only giving certificates to the owners of a domain.

Re:Sometimes

[J-F Mammet]

It depends on who will issue the certificate. Serious companies like Network Solution, Thawte or even Godaddy will send a validation email to the owner of the domain (if it's listed in the whois data) or require you to create a new file on the web site or a DNS CNAME to prove that you have admin right on the domain. It's a bit of a pain in the ass when you are registering SSL certs for a third party partner, but it's rather safe.
Some SSL companies though will simply ask you to provide an email for that domain and send a validation link to that email. So you could create ssladmin@hotmail.com and they would happily create you a perfectly valid SSL certificate for hotmail.com you could use for man in the middle attacks.

This is nothing new

[jgreco]

This is nothing new, we've been talking about issues like this since the introduction of SSL. Either you have onerous and thorough verification, which makes SSL a real pain to deploy and discourages adoption, or you have an easy-to-game system that makes SSL less secure. Security always involves lots of effort, and that's simply at odds with the way things are "supposed to work" on the Internet.

Re:Sometimes

[Wannabe Code Monkey]

So you're saying I can send an email to a root CA, and as long as the clear, unsigned from field looks serious they'll sign my cert for a domain? Can you DEMONSTRATE this? TFA sure didn't.

You sure are angry for a Sunday morning. From the Betanews article:

1. Find a free Web mail provider.
2. Register an account such as ssladmin.
3. Go to RapidSSL.com and buy a certificate. When given the choice of what e-mail address to use, simply select ssladmin.
4. Go through certificate registration process (this takes about 20 minutes).
5. You will now have a secure Web certificate for that Web mail provider

So, it's not the attacker sending an email from ssladmin@example.com to the certificate authority asking for a cert that does it. It's the attacker telling the certificate authority that ssladmin@example.com should be used to prove control over of the domain, then RapidSSL.com would send a confirmation email to that address assuming it was under control of the right people. I guess ssladmin is on a predetermined list of email addresses they allow for authentication.

In his own tests, Seifried says, it usually took only a half-hour to acquire a perfectly valid certificate for a major Web mail service.

So, yes, he can demonstrate this.