[cabfpub] [EXTERNAL] Brazilian bank DNS heist

Bruce Morton Bruce.Morton at entrustdatacard.com
Thu Apr 6 23:52:14 UTC 2017

What if the bank used EV and there was an error if there was no EV certificate?

Could this be done by using something like an HSTS header which also stated EV-only? When the Subscriber receives a DV certificate, but has stored a header for EV-only, then there would be a browser error.

Sounds like a great argument for a bank to require identity and authorization, rather than just domain control.


From: Public [mailto:public-bounces at cabforum.org] On Behalf Of philliph--- via Public
Sent: Thursday, April 6, 2017 1:46 PM
To: CA/Browser Forum Public Discussion List <public at cabforum.org>
Cc: philliph at comodo.com
Subject: [EXTERNAL][cabfpub] Brazilian bank DNS heist

Several folk have asked me to take a look at this:


What happened here was that a hacker took over a banks DNS settings for 5 hours and performed an extended phishing attack. They then acquired certs for the domain while they had control of it. So accepting that this is one incident, albeit one likely very typical of things to come, could CAA have helped?

As it stands, the answer is no because CAA is signaled through the DNS and so the attackers could control those as well. DNSSEC doesn’t help either and nor does CT as presently specified. Pinning does solve this one specific problem but only on TOFU terms.

Some observations:

* Any solution is going to have to involve some form of forward acting statement ‘do this for the next X hours’.

* We now have two mechanisms that are viable as publication infrastructures - DNS and CT.

* The problems with pinning are real, very few companies can risk shutting themselves down for an extended period if they goof. The problem with pinning is that the time period really does need to be fairly long if it is to be any use. I do not visit my bank every day. I probably don’t visit for a month at times.

* A weaker criteria such as ‘must get an EV cert’ or a much shorter time period than is needed for pinning (24 hours) is much more likely to be acceptable

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