Security Is a Weakest-Link Problem

Abstract

Attackers are more likely to attack a system at its weak points, which makes knowledge of the weakest link critical. In part this depends on knowing your likely attackers: What’s the weakest link for a suicide bomber will be different from the weakest link for a petty burglar. All systems have a weakest link, and there are several general strategies for securing systems despite their vulnerabilities. Defense in depth ensures that no single vulnerability can compromise security. Compartmentalization ensures that a single vulnerability cannot compromise secure entirely. And choke points reduce the number of potential vulnerabilities by allowing the defender to concentrate his defenses. In general, tried and true countermeasures are preferable to innovations, and simpler overlapping countermeasures are preferable to highly complex stand-alone systems. However, because attackers inevitably develop new attacks, reassessment and innovation must be ongoing.