Secure execution of Java applets using a remote playground

摘要

Mobile code presents a number of threats to machines that executenit. We introduce an approach for protecting machines and the resourcesnthey hold from mobile code and describe a system based on our approachnfor protecting host machines from Java 1.1 applets. In our approach,neach Java applet downloaded to the protected domain is rerouted to andedicated machine (or set of machines), the playground, at which it isnexecuted. Prior to execution, the applet is transformed to use thendownloading user's Web browser as a graphics terminal for its input andnoutput, and so the user has the illusion that the applet is running onnhis own machine. In reality, however, mobile code runs only in thensanitized environment of the playground, where user files cannot benmounted and from which only limited network connections are accepted bynmachines in the protected domain. Our playground thus provides a secondnlevel of defense against mobile code that circumvents language-basedndefenses. This paper presents the design and implementation of anplayground for Java 1.1 applets and discusses extensions of it for othernforms of mobile code, including Java 1.2