JavaAppletSecurity.ppt

Java Applet Security Diana Dong CS 265 Spring 2004 The Problem Millions of users download Java applets everyday, sometimes without prior approval from the user How to ensure malicious applets will not wreak havoc on the local machine? Sandbox Idea A place where Java applet code can be executed, but no areas outside of the sandbox can be accessed by the applet. Removes the responsibility of checking applet source from the user Ensures execution of malicious applet will not do damage to the local machine Sandbox contd Sandbox prohibits: File system access Network access Creation of process Process acess 4 Major Components of the Sandbox Java Virtual Machine (JVM) built-in features Class loader Class file verifier Security manager JVM Built-in Features Type-safe reference casting Structured memory access (no pointers) Automatic garbage collection (cant explicitly free allocated memory) Array bounds checking Class Loader Responsible for importing binary data that defines the running programs classes and interfaces Two types of class loaders: primordial class loader and class loader objects Class Loader contd Primordial class loader loads trusted classes, such as the Java API. Classes that are loaded this way becomes part of the JVM. Class loader objects are untrusted objects loaded into the JVM and instantiated like any other object Class Loader contd Class Loader contd How does it protect? Prevents malicious code from interfering with benevolent code – namespace. Classes are loaded into its own namespace. No access to other classes outside of its own namespace. It guards the borders of the trusted class libraries. Customizable. Class Verifier Checks the integrity of the class file to ensure no illegal bytecodes have been added Uses built-in theorem prover to check integrity Class Verifier 4 passes Class file is read into interpreter and basic format of class file is checked Additional verification of the class file without looking at the bytecodes Bytecode veri