Sidewinder: Defense in depth using type enforcement
Abstract Sites use firewalls to defend against external attacks while providing necessary Internet services. Firewalls make a site safer: They present a smaller risk since they provide fewer services. However, most firewalls use standard computer operating systems. This can allow an attacker to overrun the firewall if a known security flaw is present. The Sidewinder(TM) firewall system overcomes this problem using type enforcement. Network server applications operate in independently controlled compartments called domains, each granted specific permission to access particular types of files or communicate with other domains. If a server succumbs to an attack, type enforcement restricts the amount of damage an attacker can do. In particular, Sidewinder prevents an attack on an Internet server from accessing domains serving internal, protected networks. An attacker cannot overrun a Sidewinder because the type enforcement restrictions cannot be disabled while the system is handling network traffic.