Penetration Testing mailing list archives

Re: username and Password sent as clear text strings


From: "Matthew Zimmerman" <mzimmerman () gmail com>
Date: Wed, 21 May 2008 14:40:52 -0400

David, Marvin Simkin said it well; I didn't.

On Tue, May 20, 2008 at 4:43 AM, David Howe
<DaveHowe.Pentest () googlemail com> wrote:
Matthew Zimmerman wrote:

In my opinion, if you want to mitigate this, don't use passwords.  Use
true challenge-response.  Everything else proposed here is either
obfuscation or doesn't really work in a web application environment.
A VPN around a webserver only works if every user that needs access to
that webserver can also access the vpn.

that is unfortunately only security though obscurity, and barely worth doing
- it raises the bar quite a bit (in that the MiTM attacker must also modify
the transmitted page to request a plaintext password instead. a much more
demanding task than just recording traffic) but requires that you send
javascript, java or flash code to actually do the challenge-response
protocol (and manage the inevitable clients who will have that turned off
then complain that your site "requires" things they consider a security
issue).
Maybe I didn't state it correctly, challenge/response was the wrong
term to use.  PKI, SecurID, etc.  Something that involves something
you are or something you have in addition to something you know (e.g.,
a password).  You are correct that obfuscating the password by some
client side script/addon will not work.  That was not my intention.

 Ultimately though, if your attacker can successfully read and modify the
browser channel (either using browser plugins or indirectly by intercepting
and modifying the page stream via a MiTM attack) or intercept the data entry
channel (keyboard/mouse) you have already lost.
Right.  You break the SSL tunnel, you also have the user's cookie,
which means you don't care about a "password" anymore.  The cookie is
your password.


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