TY - CONF AB - ``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. AD - Berkeley, CA, USA AU - Sun, Ruimin AU - Porter, Donald E. AU - Oliveira, Daniela AU - Bishop, Matt T2 - Proceedings of the 15th Workshop on Hot Topics in Operating Systems Y2 - May PB - USENIX Association T1 - The Case for Less Predictable Operating System Behavior UR - https://www.usenix.org/conference/hotos15/workshop-program/presentation/sun PY - 2015 ER -