A least privilege model for static separation kernels

Abstract

We extend the separation kernel abstraction to represent the enforcement of the principle of least privilege. In addition to the inter-block flow control policy prescribed by the traditional separation kernel paradigm, we describe an orthogonal finer-grained flow control policy by extending the protection of elements to subjects and resources, as well as blocks, within a partitioned system. We show how least privilege applied to the actions of subjects and resources provides enhanced protection for secure systems, and how only trusted subjects may cause certain information flows between partitions. A high assurance separation kernel based on least privilege can provide all of the functionality and protection of the traditional separation kernel, combined with a high level of confidence that the effects of subjects' activities can be minimized to their intended scope.