Independence from obfuscation: A semantic framework for diversity *

Abstract

A set of replicas is diverse to the extent that they implement the same functionality but differ in their implementation details. Diverse replicas are less likely to succumb to the same attacks, when attacks depend on memory layout and/or other implementation details. Recent work advocates using mechanical means, such as program rewriting, to create such diversity. A correspondence between the specific transformations being employed and the attacks they defend against is often provided, but little has been said about the overall effectiveness of diversity per se in defending against attacks. With this broader goal in mind, this paper gives a precise characterization of attacks, applicable to viewing diversity as a defense, and also shows how mechanically-generated diversity compares to a well-understood defense: type checking.