This project is developing an automated defense system for enterprise networks against malicious code attacks such as worms, viruses and spyware. This system responds to attacks by dynamically and selectively quarantining hosts, services, and other networked devices. Traditional containment systems based on firewalls and individual host isolation are not adequate for containing the new generation of local-scanning, topological, metaserver and contagion worms that can spread very quickly through an enterprise.