The Case for Less Predictable Operating System Behavior

“No one is so brave that he is not disturbed by something unexpected.” Julius Caesar

The operating system is increasingly regarded as untrustworthy. Applications, hardware, and hypervisors are erecting defenses to insulate themselves from the operating system. This paper explores the potential benefits if operating systems simply embraced these lowered expectations and deliberately varied API behavior. We argue that, even for trusted or benign applications, diversity roughly within the specification can improve resilience to attack and improve robustness. Malicious software tends to be brittle; a preliminary case study indicates that, for software of questionable origin, a somewhat hostile operating system may do more good than harm for system security. This paper describes the architecture of Chameleon, an ongoing project to implement spectrum behavior as an operating system feature.