nationwide interception of Facebook & webmail login credentialsin Tunisia

[David Biggins]

I suspect that the answer is "almost everybody".

 

The related question would also he "how many people review their
installed root certificates after windows updates?"  and the answer to
that is probably "almost nobody".

 

And it wouldn't necessarily have helped at various times if you did - XP
at one point had as default a feature that automatically and silently
reinstated them.   [ http://www.proper.com/root-cert-problem/  ]

 

 

D.

 

From: ukcrypto-bounces at chiark.greenend.org.uk
[mailto:ukcrypto-bounces at chiark.greenend.org.uk] On Behalf Of Mark Lomas
Sent: 23 March 2011 9:05 PM
To: UK Cryptography Policy Discussion Group
Subject: Re: nationwide interception of Facebook & webmail login
credentialsin Tunisia

 

This story reminds me of something I said in January (and in about
2000):

http://www.theregister.co.uk/2011/03/23/gmail_microsoft_web_credential_f
orgeries/

 

        Mark

 

On 26 January 2011 09:18, Mark Lomas <ukcrypto at absent-minded.com> wrote:

Some years ago (probably in 2000) I persuaded a major bank to remove the
majority of CA certificates from the key store of the browser they had
deployed.

 

The IT department regarded the change as a nuisance, but the Legal
department understood the problem as soon as I showed them the list of
CAs.

 

May I conduct an informal survey? Who on this mailing list has not
removed any of the CA certificates that were pre-installed by whoever
supplied your browser?

 

        Mark

 

On 25 January 2011 20:24, Ian Batten <igb at batten.eu.org> wrote:


On 25 Jan 2011, at 16:18, Passive PROFITS wrote:

> That would not deal with the falsifying of certificates.  Assuming the
code-base of this is not intentional corrupt, the addition of an
extension such as certpatrol is also required (a firefox extension), to
notify one when the SSL cert swap by the government/ISP (using the
browser accepted as 'true' passported C.A.(s) under their control) has
taken place (a MiTM is in progress notification function).  The other
known way would be manual/local (each time) inspection of the cert
fingerprint(s).  e.g. you note Facebook's fingerprint then check each
time it's got the same 'print.  Then (once under notice the hack is
under progress) you could retreat, or start playing your own pre-planned
counter-measures ... depending on the peril of the situation, tactics,
etc, call the government, depending on the nature of your business, etc.

There's been some recent, if un-startling, discussion of this:
http://www.freedom-to-tinker.com/blog/sroosa/flawed-legal-architecture-c
ertificate-authority-trust-model

I suspect that once you have more than a handful of CAs, it's for
practical purposes impossible to get any meaningful assurance that they
are all legitimate.   If CAs delegate their authority, it's difficult to
even know that certificates whose chain of trust goes back to a CA you
trust was actually issued by that CA.  And for as long as any CA can
issue a certificate in any name, any domain can be subverted by any one
of the CAs.

Which means that certificates are as weak as the weakest CA you trust,
unless that CA in turn trusts a yet weaker CA.

I've not looked at this in detail (perhaps I should) but I think it's
possible in most browsers to trust _no_ CAs and yet trust individual
certificates, which might have the required semantics: when a
certificate is encountered, you check it (by whatever out of band
mechanism you deem appropriate) and then add it to your certificate
store, but you do not add its certifying keys.

ian



 

 

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