The defense techniques employed by large software manufacturers are getting better. This is particularly true of Microsoft who have improved the security of the software they make tremendously since their Trustworthy Computing initiative. Gone are the days of being able to penetrate any Microsoft system by firing off the RPC-DCOM exploit. The consequence of this is that post-exploitation has become increasingly important in order to "squeeze all the juice" out of every compromised system. Windows access tokens are integral to Microsoft's concept of single sign-on in an active directory environment. Compromising a system that has privileged tokens can allow for both local and domain privilege escalation.
