(SPAM: 5.454) Re[6]: [security] [dix] Re: Gathering requirements for in-browser OpenID support

[Ben Laurie]

On 31/10/06, Chris Drake <christopher at pobox.com> wrote:
> Hi Ben,
>
> For the benefit of me and others reading this thread, can you briefly
> explain how you would deploy EKE in a browser to defeat MitM ?
>
> Lets assume I set up a MitM site - https://www.paypal.com.phisher.com
> and I even bother to buy a $38 SSL cert for it.  Next - I install a
> CGI script here which grabs the real PayPal site, adjusts references
> to paypal.com so they read "paypal.com.phisher.com" (eg: form POST
> targets), and send this to the phish victim. *.phisher.com is now the
> "Man in the Middle" between PayPal, and victim.
>
> I call this a "stupid user" problem, because the user has forgotten to
> check they're on the correct URL.  Everything else (except windows
> password auto-complete) acts & looks legit.

So much better to blame the user than to construct a system where the
user is not vulnerable to this problem, isn't it?

> Now - Encrypted Key Exchange solves this problem by: [insert your
> explanation here] ?

By ensuring that the man in the middle:

a) Ends up not in the possession of any authentication credentials

b) Can neither understand nor usefully modify the conversation they
are proxying.


>
> Kind Regards,
> Chris Drake
>
>
> Monday, October 30, 2006, 10:05:11 PM, you wrote:
>
> BL> On 28/10/06, Chris Drake <christopher at pobox.com> wrote:
> >> Hi Ben,
> >>
> >> Apart from that blog where the blogger didn't realize that all banks
> >> immediately suspend accounts that get logged in to from Russia,
> >> Eastern Europe, Asia, and more generally - anyplace other than
> >> "normal" - and as such - can't ever work - no - phishing attacks are
> >> not MitM.  They're just bogus web sites that email captured
> >> credentials to hackers.  Sure - some hackers might be able to capture
> >> some token credentials, but they can't *use* them - not from Russia,
> >> and not after the 30seconds or so most token codes last for.
> >>
> >> Besides - and the most important thing really - there's no such thing
> >> that *I've* ever heard of that *can* be put into any protocol to
> >> prevent MitM attacks from succeeding.  If user A doesn't check their
> >> URL says site B when user A thinks they're on site C - then site B can
> >> merely proxy anything site C puts up, stealing whatever they want in
> >> the process.
>
> BL> Clearly you need to update your crypto knowledge. There are many
> BL> protocols that prevent MitM - for example, EKE.
>
> BL> Yes, site B can always proxy, but it doesn't help site B if he is
> BL> proxying a conversation he can't understand, by virtue of it being
> BL> encrypted.
>
> >> MitM is not a protocol problem - it's a "stupid user" problem.
>
> BL> Wrong.
>
> >>
> >> Kind Regards,
> >> Chris Drake
> >>
> >>
> >> Sunday, October 29, 2006, 2:28:03 AM, you wrote:
> >>
> >> BL> On 28/10/06, Chris Drake <christopher at pobox.com> wrote:
> >> >> BL> 2 factor auth gets you nowhere if the underlying protocols don't
> >> >> BL> protect you from MitM.
> >> >>
> >> >> What he *means* of course - is that 2-Factor auth solves pretty much
> >> >> every security problem users are likely to face in the wild
> >> >> (especially the most common and dangerous - phishing) - with the
> >> >> *exception* of Man-in-the-middle attacks, in some circumstances.
> >>
> >> BL> ? But many phishing attacks are MitM.
> >>
> >> >> It certainly doesn't "get you nowhere" - it almost always gets you
> >> >> exactly to where you want to be.
> >>
> >> BL> We seem to be drifting far from the original point, which was that the
> >> BL> protocols should protect users against MitM. 2-factor auth doesn't do
> >> BL> this, of itself. And if the protocols do provide protection, then
> >> BL> 2-factor auth defends against a rather small subset of attacks.
> >>
> >> >>
> >> >> Kind Regards,
> >> >> Chris Drake
> >> >>
> >> >>
> >> >> _______________________________________________
> >> >> general mailing list
> >> >> general at openid.net
> >> >> http://openid.net/mailman/listinfo/general
> >> >>
> >>
> >>
> >>
> >>
>
>
>
>