Java Security: Web Browsers and Beyond

The introduction of Java applets has taken the World Wide Web by storm. Java allows web creators to embellish their content with arbitrary programs which execute in the web browser, whether for simple animations or complex front-ends to other services. We examined the Java language and the Sun HotJava, Netscape Navigator, and Microsoft Internet Explorer browsers which support it, and found a significant number of flaws which compromise their security. These flaws arise for several reasons, including implementation errors, unintended interactions between browser features, differences between the Java language and bytecode semantics, and weaknesses in the design of the language and the bytecode format. On a deeper level, these flaws arise because of weaknesses in the design methodology used in creating Java and the browsers. In addition to the flaws, we discuss the underlying tension between the openness desired by web application writers and the security needs of their users, and we suggest how both might be accommodated.