"SSL stops credit card sniffing" is a correlation/causality myth

[Perry E. Metzger]

Ian G <iang at systemics.com> writes:
> On Tuesday 31 May 2005 02:17, Steven M. Bellovin wrote:
>> The next part of this is circular reasoning.  We don't see network
>> sniffing for credit card numbers *because* we have SSL.
>
> I think you meant to write that James' reasoning is
> circular, but strangely, your reasoning is at least as
> unfounded - correlation not causality.  And I think
> the evidence is pretty much against any causality,
> although this will be something that is hard to show,
> in the absence.
>
>  * AFAICS, a non-trivial proportion of credit
> card traffic occurs over totally unprotected
> traffic, and that has never been sniffed as far as
> anyone has ever reported.

Perhaps you are unaware of it because no one has chosen to make you
aware of it. However, sniffing is used quite frequently in cases where
information is not properly protected. I've personally dealt with
several such situations.

Bluntly, it is obvious that SSL has been very successful in thwarting
certain kinds of interception attacks. I would expect that without it,
we'd see mass harvesting of credit card numbers at particularly
vulnerable parts of the network, such as in front of important
merchants. The fact that phishing and other attacks designed to force
people to disgorge authentication information has become popular is a
tribute to the fact that sniffing is not practical.

The bogus PKI infrastructure that SSL generally plugs in to is, of
course, a serious problem. Phishing attacks, pharming attacks and
other such stuff would be much harder if SSL weren't mostly used with
an unworkable fake PKI. (Indeed, I'd argue that PKI as envisioned is
unworkable.)  However, that doesn't make SSL any sort of failure -- it
has been an amazing success.

>  * We know that from our experiences
> of the wireless 802.11 crypto - even though we've
> got repeated breaks and the FBI even demonstrating
> how to break it, and the majority of people don't even
> bother to turn on the crypto, there remains practically
> zero evidence that anyone is listening.

Where do you get that idea? Break-ins to firms over their unprotected
802.11 networks are not infrequent occurrences. Perhaps you're unaware
of whether anyone is listening in to your home network, but I suspect
there is very little that is interesting to listen in to on your home
network, so there is little incentive for anyone to break it.

>> As for DNS hijacking -- that's what's behind "pharming" attacks.  In
>> other words, it's a real threat, too.
>
> Yes, that's being tried now too.  This is I suspect the
> one area where the SSL model correctly predicted
> a minor threat.  But from what I can tell, server-based
> DNS hijacking isn't that successful for the obvious
> reasons

You are wrong there again.

Where are you getting your information from? Whomever your informant
is, they're not giving you accurate information.


-- 
Perry E. Metzger		perry at piermont.com

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