Introduction

We often run untrusted or complex applications on our systems.
Web browsers like opera or mozilla.
Bind daemon for DNS.

We assume that applications contain programming errors that may lead to unauthorized access.
Evil web pages may cause browser to send or delete files.
Bugs in an irc client can be used to install back doors.

Detecting or preventing compromises is difficult.
New exploit tools available.
Evasion of Network IDS.