Verification and Validation of JavaScript

JavaScript is a prototype-based, dynamically typed language with scope chains and higher-order functions. Third party web applications embedded in web pages rely on JavaScript to run inside every browser. Because of its dynamic nature, a JavaScript program is easily exploited by malicious manipulations and safety breach attacks. Therefore, it is highly desirable when developing a JavaScript application to be able to verify that it meets its expected specification and that it is safe. One of the challenges in achieving this objective is that it is hard to statically keep track of the heap-manipulating JavaScript program due to the mutability of data structures. This thesis focuses on developing a verification framework for both functional correctness and safety of JavaScript programs that involve heap-based data structures. Two automated inference-based verification frameworks are constructed based upon a variant of separation logic. The first framework defines a suitable subset of JavaScript, together with a set of operational semantics rules, a specification language and a set of inference rules. Furthermore, an axiomatic framework is presented to discover both pre/post-conditions of a JavaScript program. Hoare-style specification {Pre}prog{Post}, where program prog contains the language statements. The problem of verifying program can be reduced to the problem of proving that the execution of the statements meets the derived specification language. The second framework increases the expressiveness of the subset language to include this that can cause safety issues in JavaScript programs. It revises the operational rules and inference rules to manipulate the newly added feature. Furthermore, a safety verification algorithm is defined. Both verification frameworks have been proved sound, and the results ob- tained from evaluations validate the feasibility and precision of proposed approaches. The outcomes of this thesis confirm that it is possible to anal- yse heap-manipulating JavaScript programs automatically and precisely to discover unsafe programs

Finite Countermodel Based Verification for Program Transformation (A Case Study)

Both automatic program verification and program transformation are based on program analysis. In the past decade a number of approaches using various automatic general-purpose program transformation techniques (partial deduction, specialization, supercompilation) for verification of unreachability properties of computing systems were introduced and demonstrated. On the other hand, the semantics based unfold-fold program transformation methods pose themselves diverse kinds of reachability tasks and try to solve them, aiming at improving the semantics tree of the program being transformed. That means some general-purpose verification methods may be used for strengthening program transformation techniques. This paper considers the question how finite countermodels for safety verification method might be used in Turchin's supercompilation method. We extract a number of supercompilation sub-algorithms trying to solve reachability problems and demonstrate use of an external countermodel finder for solving some of the problems.Comment: In Proceedings VPT 2015, arXiv:1512.0221