Hey guys,
I recently got round to writing the whitepaper version of my Defcon 15 and CCC
talk. For those who are interested, please find the abstract, PDF link and
sourceforge link to the accompanying tool below: -
http://www.mwrinfosecurity.com/publications/mwri_security-implications-of-windows-access-tokens_2008-04-14.pdf
http://sourceforge.net/projects/incognito
ABSTRACT
This whitepaper discusses the security exposures that can occur due to the
manner in which access tokens are implemented in the Microsoft® Windows
Operating System. A brief overview of the intended function, design and
implementation of Windows access tokens is given, followed by a discussion of
the relevant security consequences of their design. More specific technical
details are then given on how the features of Windows access tokens can be used
to perform powerful post-exploitation functions during penetration testing,
along with a basic methodology for including an assessment of the
vulnerabilities exposed through tokens in a standard penetration test.
Discussion is also included about why many corporate environments (assessed
during penetration tests conducted by MWR InfoSecurity) have been found to not
be operating in a manner which limits the risk of such issues. Finally, best
practice advice is given on how to defend against these attacks.
It must be noted that the security issues discussed in this white paper do not
represent a flaw in the Microsoft® Windows Operating System but are an expected
consequence based on the design and implementation of Windows access tokens.
The important point is that many corporate environments do not account for
these issues within their security strategy and, consequently, the controls in
many of these environments are not sufficient to withstand the techniques
discussed here.
Additionally, it is acknowledged that the security implications of Windows
access tokens have been discussed before both in general terms and to different
degrees of technical detail. This document is not intended to present such
discussions as being fundamentally new; instead it is intended to collate some
of the existing knowledge, introduce some new findings and to demonstrate why
many years after the general principles discussed were highlighted, many
corporate environments are still vulnerable to these issues.
This paper is based upon research originally presented by the author at Defcon
15 [1] and Chaos Computer Congress (CCC) 2007 [2].
Cheers,
Luke
