... advantages of end-to-end Web application security and of our proposed mechanism.1 Introduction Web applications provide end users with client access toserver functionality through a set of Web pages. ... client Web browser.Most Web applications aim to enforce simple, intu-itive security policies, such as, for Web- based email, dis-allowing any scripts in untrusted email messages. Evenso, Web applications ... and to secure the emerging class of rich, cross-domain Web applications referred to as Web 2.0.In order to support end-to-end security, Web clientsmust be enhanced. We introduce Mutation-Event...