Full Disclosure mailing list archives

Re: Creating a rogue CA certificate


From: Valdis.Kletnieks () vt edu
Date: Tue, 30 Dec 2008 16:42:47 -0500

On Tue, 30 Dec 2008 16:13:07 EST, Elazar Broad said:
And they should have listened then, it was only a matter of time
before someone fleshed out a practical attack, and that time is
now. Then again, I am sure there some ATM's out there still using
DES. How many time's do we need to prove Moore's law...

Playing devil's advocate for a moment...

And perhaps they *were* listening, but realized that security is about
tradeoffs, and they balanced the cost of doing the upgrade back then
against the chances that a team as technically and budget-wise prepared
as this one, *and with nefarious intent*, would do something significantly
drastic enough to dent their revenue stream.

Read section 5.2 of the hashclash/rogue-ca paper.  The victim CA is churning
out an average of 1,000 certs in 3 days, let's say at $12 per. That's some
$600K per year for just the weekends, not counting the Mon-Thurs span which
is probably even higher (and why they targeted a weekend).  So $2M per year
or more.

Who wants to place a bet that said CA will be selling *the same number*
of certs every week, meaning they had *no* economic loss due to this hack,
because their customers won't actually *see* the news article and give them
a bad feeling about their CA?  And with no actual loss, why spend the money
to implement the change?

Hint: It *isn't* just a matter of changing one line in a script to say
'sha1' instead of 'md5' - you *also* need to go back and look at all the
certs you've issued already and figure out if they've been tweaked...

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