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.

Supported by the National Natural Science Foundation of China under Grant No.60373054 and No.60073022; the National 863 High-tech Program of China under Grant No.2002AA141080; the Science and Technology Program of Haidian District under Grant No.K20044803.