BugTraq
RE: Re: secure client-side platform Sep 01 2005 07:19PM
Mark Senior (Mark Senior gov ab ca)
Your attack tree below is of the form:
A and ( B or C or D) and E

I submit a simpler one of the form:
A or (B and C)

A - there is an exploitable vulnerability (in the remote-code-execution
sense) in the DNS response handling code on your livecd. You send out a
query, a malicious response reaches you before the real one & gets
through the firewall, and you're done.

OR
B - There is an exploitable vulnerability in the public key
verification process in the browser on your livecd. This vulnerability
could be a remote-code-execution vulnerability, or it could be limited
to causing the browser to present a certificate as legitimate when it
isn't. AND

C - The attacker is able to redirect you to a malicous https
server by e.g. DNS, ARP, or routing protocol attacks somewhere upstream.

C should be pretty much taken as a given, otherwise why bother with SSL
at all?

Regards
Mark

> -----Original Message-----
> From: liudieyu umbrella.name [mailto:liudieyu umbrella.name]
> Sent: August 31, 2005 21:25
> To: bugtraq (at) securityfocus (dot) com [email concealed]
> Subject: Re: secure client-side platform
>
>
>
> #1, we are talking about how to do critical secret
> communication in a secure way, right? so forget about those
> putting win9x 24/7 on DSL ... let them continue contributing
> to the spam and zombie business ;-)
>
> imagine i'm going to access an e-gold acocunt of $1M ...
> first i unplug the network cable and remove harddrive;
> then boot with a clean livecd;
> later start firewall and then plug the network cable;
> run "mozilla-firefox about:blank";
> directly go to HTTPS-secured website;
> once done, reboot.
> i cannot figure out what could go wrong in the above process ...
>
> clean read-only OS is a solution against "once owned, stay
> owned" (trojan stays in system until next format)
>
> it does not solve the problem of the vulnerabilities in
> client software like mozilla (as joxean and keith suggested)
>
> if we only have encryption-secured connection to trusted
> server, assuming enemy do not have control over the trusted
> server itself, our computer can only be compromised if:
> * enemy have total control over the communication channel
> between us and the trusted server
> * AND
> - there is a vulnerability in the certificate/publickey
> verification process of client software like mozilla
> - OR the mathematic foundation of publickey-privatekey
> sign/encrypt trick got a problem.
> - OR we clicked YES in the
> certificate-is-invalid-continue-or-not dialog
> * AND
> enemy got vulnerability to exploit after going thru the
> certificate verification process taken in our side.
>
> chances are rare, hum? the very last sentence of my trooseid
> article is:
> Never touch any not-encryption-secured connection during a
> secret-communication op.
> you read it, right?
>
> Q: can you really trust Google?
> A: it's really up to you which server you choose to store and
> transfer encrypted secrets. in my view, the Gmail service of
> google is just a good example here ... you got service better
> than google's gmail, of course go ahead ... )
>
> honestly, i have not used the tools mentioned in the "why not
> ... " part below. it gonna take some time to evaluate those
> solutions by myself.
>
> ####################
>
> "you got a problem"
> *** 1 ***
> Joxean Koret <joxeankoret (at) yahoo (dot) es [email concealed]> [+] I think
> this is a bad idea. What about client software vulnerabilities?
> You can have a system that were secure but
>
> currently it's not.
> [+] Various applications, such as web browsers, mail
> clients, etc... needs to be constantly updated to fix the newest
>
> vulnerabilities.
> *** 2 ***
> "Keith Oxenrider" <web10198 (at) sol-biotech (dot) com [email concealed]> [+] I
> am sure you will be hearing this from many others, but
> basically it is impossible to secure client side computing if
>
> the client every goes outside of your control (one presumes
> that if it remains inside your control you have effective
>
> controls). Clearly, server side computing is entirely within
> the control of whomsoever owns (or 0wns) the server, so there
>
> is implicit trust when you connect (can you really trust
> Google to protect your content?).
> [+] While your recommendations, if used, will obviously
> increase the baseline security of the average person, you can't
>
> guarentee anything. Smart card developers run into many of
> these issues and they don't have to deal with buggy commodity OSs
>
> and browsers. Since the vast majority of users don't even
> bother to keep their machines patched (people STILL use Win9x
>
> connected 24/7 to DSL, btw), offering suggestions on how to
> make their computer even more difficult to use is unlikely to win
>
> any converts.
> [+] Those of us who are already paranoid and have done their
> homework know there is no way to ensure on-line security
>
> besides never doing anything on-line.
> [+] Something to keep in mind, a read-only OS is only as
> good as its patch level when it was written and will decay with
>
> time eventually (soon) reaching an insecure state that can
> easily be penatrated.
>
>
> "why not ..."
> *** 1 ***
> Joxean Koret <joxeankoret yahoo.es> Why not use a
> system like LTSP (Linux Terminal Server Project) or any other
> "Think Client" based system?
> *** 2 ***
> "Beauford, Jason" <jbeauford EightInOnePet.com>
> Tinfoil Hat linux ..silly. http://tinfoilhat.shmoo.com/
> *** 3 ***
> "Gustavo Paredes" <gustavo.paredes internet-solutions.com.co>
> Do you know secuware? www.secuware.com
>
> ####################
>
> how to have a secure client-side platform for secret communication?
> ... transferring and storing secret messages, online banking, etc
>
> i got some fresh ideas in mind, and would like to share it here:
> 0. watch network with sniffer, so be sure no byte is sent to
> weird destinations 1. read-only operating system(knoppix,
> etc), so every boot is a fresh start 2. get every secret
> processed in memory and stored as encrypted in remote server
>
> any suggesion or fresh idea on this topic is welcome
>
> this document for ordinary people on the street:
> http://umbrella.name/upid/trooseid
>
> bugtraq guys can directly go to the conclusion part:
> http://umbrella.name/computer/trooseid/trooseid_online/#conclusion
>
>

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