Ian Grigg wrote:
Costs are still way too high. This won't change until
browsers are shipped that treat self-signed certs as being
valid. Unfortunately, browser manufacturers believe in
cert-ware for a variety of non-security reasons.
[...]
Jason Holt [EMAIL PROTECTED] wrote:
Self signed certs defeat the purpose of the certificate chain mechanism, which
is not just there to make Veri$ign rich.
I understand that we are all working to make Veri$ign rich by
pushing their cert-ware. Let me offer you a way in which we
could make them richer. Believe me, they need our help.
Mallory can self-sign a cert for
bob.com, and hack Alice's DNS to point bob.com at her own site. But it's
(theoretically, anyway) much more difficult for her to convince Verisign that
she owns bob.com. If we trust Verisign to do that, then we know we're really
talking to Bob when we visit bob.com.
What you describe above is an arcane theoretical attack.
An MITM is an extraordinarily difficult thing to do. In
practice, totally impractical in risk analysis terms. Its
impracticality is because there are always easier pickings
out there than conducting this attack.
Consider the attack. You have to be able to so some spoofing,
or some interception, or some hacking of critical infrastructures
to do this. After all, you have to be able to insert yourself
where Mallory needs to be in some sense, which means perverting
the normal flow of packets.
This is generally highly risky. It is also expensive and
hard to control.
Say you are attacking Amazon. If you pervert the DNS, as
you suggest, you will have to be able to handle a lot of DNS
requests. Also, there is a high chance that you will be
noticed. Net techies and hackers and ISP people are looking
at this sort of thing all the time.
Now consider what you get: you can sit in the middle and
manage some SSL traffic. So you'll need some capacity to
sift through all the different sessions to snaffle the good
data. At the end of the day, you'll be burning up a lot of
CPU cycles to manage that traffic. (So you'll need access
to some good sized hardware if you are attacking Amazon.)
Finally, you manage to start farming those valuable CCs.
Depending on how much hardware you've got that is managing
the thousands of MITM sessions, you could pick up quite a
bunch.
But, if you do manage to get to the point of actually
harvesting some CCs, you will by now have laid out such
a road map that someone should be able to find you. So,
you had better have a fast exit.
Here's the thing: even if you get some, it wasn't worth it.
Think like a crook. Any thing that you can do with SSL,
you can do easier just by hacking into some poor NT box and
accessing the database to read off the CCs. Then you get
to walk away without leaving any tracks. Then you get the
last month's takings, because the company already did the
harversting for you.
And, in practice this is how it goes. No thief ever bothers
to do an MITM, even over *un*encrypted traffic. They simply
hack into the machines and steal it all. That's why there
has never been a case of CCs sniffed over the net and being
used to commit a fraud (at least, no recorded ones).
Change the analysis to small merchants, and it is even worse
(of course Amazon will have a cert, so even its rich bounty
is unavailable, you have to do this on small merchants).
So, how do we make Veri$ign richer? Easy, switch browsers
to accepting self-signed certs. To see this, we have to
have tried or heard about small enterprises who have tried
to set up their SSL certs.
It's very expensive. Most don't do it. If we had the money
we could ask Netcraft.com for the figures, but, last I checked,
only 1% of servers have proper setups with proper certs. Why?
because it is so expensive to set up.
Most sites try and fail. They give up when they realise it
isn't worth their time. So Veri$ign fails to sell the cert.
And the site remains unencrypted, uncerted, unprotected only
by the fact that nobody is watching. (Security by obscurity
is indeed the greatest friend that we have, by actual saved
amounts of money.)
Now, if there was a halfway house, the site could at least
be set up so that it is encrypted. Right there, is a big
improvement in security. If we could do that, if we could
encourage the browsers to accept the self-signed but
encrypted web sites, that would let all the poor people in
the world (the other 99% that can't afford all the hoo-haa
of dealing with VeriSign and techies and ISPs and ...) have
a go at setting up secure web sites. Secure by encryption
that is.
My guess is that it would get the number up to 10%. Why
would that make Veri$ign richer? Because taking that 10%
of encrypted sites would be a much more powerful target
market. Veri$ign knows they care. Those sites just haven't
got around to doing the work to get the cert set up. But
they are encrypted. They are half way there. They want to
be there!
A
