Enforcing the principle of least privilege with a state-based privilege control model

Abstract

In order to provide effective support to the principle of least privilege, considering the limitation of traditional privilege mechanisms, this paper proposes a new privilege control model called State-Based Privilege Control (SBPC) and presents the design and implementation of a prototype system for SBPC called Controlled Privilege Framework (CPF) on the Linux operating system platform. SBPC decomposes the time space of a process' lifetime into a series of privilege states according to activities of the process and its need for special permissions. The privilege state is closely related to the application logic of a process. It is the privilege state transfer event that stimulates a process to transfer from one privilege state into another one. For a specified process, there is a specific set of privileges corresponding to every privilege state of the process. With the implementation of CPF, experiment results show that fine-grain and automatic privilege control can be exercised transparently to traditional applications, threats of intrusion to a system can be reduced greatly, and support to the principle of least privilege can therefore be achieved effectively. © Springer-Verlag Berlin Heidelberg 2005.