Policy-based protection against external programs via code transformation
Raju Panday, Brant Hashii · 2004
There is considerable interest in programs that can migrate from one host to another and execute. Mobile programs are appealing because they support efficient utilization of network resources and extensibility of information servers. However, since they cross administrative domains, they have the ability to access and possibly misuse a host's protected resources. This dissertation examines the security problems that result from mobile programs as well as a number of solutions to the problem. It then presents a novel approach for controlling and protecting a site's resources. In this approach, a site uses a declarative policy language to specify a set of constraints on accesses to resources. A set of code transformation tools enforces these constraints on mobile programs by integrating the access constraint checking code directly into the mobile program and resource definitions. Because our approach does not require resources to make explicit calls to a reference monitor, it does not depend upon a specific runtime system implementation. Further, it does not require that sites include explicit calls to reference monitors in resource definitions. The performance analysis show that the approach performs better than calling a reference monitor in certain cases. We then extend this approach to allow the declared security policy to be dynamically altered. We also examine how to use this approach to specify and enforce common security policy models.