SafeJS: Hermetic Sandboxing for JavaScript

Isolating programs is an important mechanism to support more secure applica-tions. Isolating program in dynamic languages such as JavaScript is even more challenging since reflective operations can circumvent simple mechanisms that could protect program parts. In this article we present SafeJS, an approach and implementation that offers isolation based on separate sandboxes and control of information exchanged between them. In SafeJS, sandboxes based on web workers do not share any data. Data ex-changed between sandboxes is solely based on strings. Using different policies, this infrastructure supports the isolation of the different scripts that usually popu-late web pages. A foreign component cannot modify the main DOM tree in unex-pected manner. Our SafeJS implementation is currently being used in an industrial setting in the context of the Resilience FUI 12 project.