Automated verification of security policies in mobile code

This paper describes an approach for the automated verification of mobile programs. Mobile systems are characterized by the explicit notion of locations (e.g., sites where they run) and the ability to execute at different locations, yielding a number of security issues. We give formal semantics to mobile systems as Labeled Kripke Structures, which encapsulate the notion of the location net. The location net summarizes the hierarchical nesting of threads constituting a mobile program and enables specifying security policies. We formalize a language for specifying security policies and show how mobile programs can be exhaustively analyzed against any given security policy by using model checking techniques. We developed and experimented with a prototype framework for analysis of mobile code, using the SATABS model checker. Our approach relies on SATABS's support for unbounded thread creation and enhances it with location net abstractions, which are essential for verifying large mobile programs. Our experimental results on various benchmarks are encouraging and demonstrate advantages of the model checking-based approach, which combines the validation of security properties with other checks, such as for buffer overflows.