RE: Can you impersonate a client side cert??

["L Williams" <eldub () pobox com>]

Darren,

This needs a certificate-usage context to be relevant. For example, SSL
had some "man and the middle" attacks that were addressed in later
versions of the protocol and in all versions of TLS.

Sometimes web-based applications use the DN to pass user context from
the web server to the application. If a person does not clear out the
trusted certificates from the web server (meaning removing any unused
trusted root), you could get a cert from Verisign and I could get a cert
from Thawte that have the same DN, both would be accepted during the SSL
session and the application would receive the same DN as the user
context.

For this to work, it requires:
- The use of the DN as a way of passing user context (which is stupid
and not generally done)
- Misconfiguration of the web server

-Laudon
eldub (at) pobox (dot) com
eldub (at) securityarchitects (dot) net


 

-----Original Message-----
From: Darren Craig [mailto:darren.craig () celare co uk] 
Sent: Monday, January 28, 2002 4:00 AM
To: pen-test () securityfocus com
Subject: Can you impersonate a client side cert??

Hi All,


I have been reading a paper which was published back in Feb 2001 by a
company call Sensepost which says that there is a way to impersonate a
users
client side cert by using the same common name. Does anybody have any
experience of doing this or is it even possible considering that the
users
public part of the cert would be installed on the web server?

Darren



----------------------------------------------------------------------------
This list is provided by the SecurityFocus Security Intelligence Alert (SIA)
Service. For more information on SecurityFocus' SIA service which
automatically alerts you to the latest security vulnerabilities please see:
https://alerts.securityfocus.com/