On 10/08/15 11:28, Ben Laurie wrote:
On Sat, 8 Aug 2015 at 17:56 Bryan Ford <[email protected]
<mailto:[email protected]>> wrote:
Hi Tom,
On Aug 6, 2015, at 11:46 AM, Tom Ritter <[email protected]
<mailto:[email protected]>> wrote:
<snip>
The Comodo incident you reference, was that the mozilla.com
<http://mozilla.com> cert in
2008? That was someone just trying a RA portal and getting a cert:
http://www.theregister.co.uk/2008/12/29/ca_mozzilla_cert_snaf/
Despite all the effort to find such certs manually, via MEKAI,
Perspectives, Convergence, Cert Patrol, and others - I'm not aware of
anyone ever catching a CA-signed misissued cert manually.
I think it was the March 2011 incident, where a hacker was able to
obtain fraudulent certificates through Comodo and then apparently
attempted to use at least one of them, for ‘login.yahoo.com
<http://login.yahoo.com>’, in some way:
https://www.comodo.com/Comodo-Fraud-Incident-2011-03-23.html
Comodo’s report and the other information I found don’t make it
clear exactly in what way the login.yahoo.com
<http://login.yahoo.com> cert was “seen live on the Internet” -
perhaps it was Google pinning as well if Google was pinning Yahoo’s
certs at that time (were they?), or perhaps it was manual
forensics. Perhaps you or someone else has better information about
this. But this is all incidental: it’s great that Google pinning
has caught a lot of incidents, but nobody seems to be saying that
means Google pinning is the best/final solution.
In this case, though, CT would have caught the mis-issue.
Had we (Comodo) been submitting all certs to CT logs at that time, then
yes, CT would have caught these mis-issues.
Had Chrome been doing certificate pinning at that time (which I don't
think it was, given that
https://www.imperialviolet.org/2011/05/04/pinning.html is dated a couple
of months later), it would have caught these mis-issues too, if any
Chrome users had actually been exposed to any of these certs "live on
the Internet".
The "seen live on the Internet" claim: Within a few hours of us noticing
the mis-issuances, we'd analyzed our webserver logs looking for activity
on the compromised account and we'd spotted some IP addresses allocated
to Iran. One of my colleagues did a port 443 scan across the relevant
IP subnets and found a server that was sending that login.yahoo.com
cert. IIRC, that server wasn't up for long.
Incidentally, this is pretty fair summary of the incident:
https://www.chromium.org/Home/chromium-security/root-ca-policy
"In March of 2011, Comodo issued fraudulent certs for a number of
well-known internet sites including Microsoft, Yahoo and Google. This
was not due to a compromise at Comodo, but rather at an authorized
Registration Authority operating on Comodo’s behalf. In that case,
Comodo immediately spotted the mis-issuance, revoked the certificates,
notified the affected parties, and made a full and public disclosure of
what had happened, albeit a week after the event. While the compromise
itself cannot be minimized, Comodo mostly acted in a manner consistent
with the trust placed in them as a Root CA (earlier disclosure would
have been better)."
My one complaint is the "mostly...earlier disclosure would have been
better" part. We wanted to disclose ASAP, but one of the browser
providers said they needed 9 days to produce and test patches. That may
sound implausible now, but remember that this was before any of the
browsers had introduced their certificate blacklisting mechanisms (i.e.
Google's CRLSets, Microsoft's disallowed.stl, etc).
--
Rob Stradling
Senior Research & Development Scientist
COMODO - Creating Trust Online
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