Data-Confined HTML5 Applications

Rich client-side applications written in HTML5 proliferate on diverse platforms, access sensitive data, and need to maintain dataconfinement invariants. Applications currently enforce these invariants using implicit, ad-hoc mechanisms. We propose a new primitive called a data-confined sandbox or DCS. A DCS enables complete mediation of communication channels with a small TCB. Our primitive extends currently standardized primitives and has negligible performance overhead and a modest compatibility cost. We retrofit our design on four real-world HTML5 applications and demonstrate that a small amount of effort enables strong data-confinement guarantees.