Mark Ladue
Proc. 20th NIST-NCSC National Information Systems Security Conference
1997
Download PDF (38.16Kb) (You need to be registered on forum)In Java's first year it has become clear that many of the problems posed by executable content have not been solved. The almost exclusive focus of the Java community on executable content has left numerous avenues unexplored for threats. It has been observed that there is no one-to-one correspondence between Java source code (programs) and Java byte code (class files). While every program written in Java can be compiled to byte code by a Java compiler, it is possible to create classfiles which no Java compiler can produce, and yet, which pass the Java Verifier with flying colors. This fact has one very serious implication -No matter what claims are made, and even formally demonstrated, for the security of the Java language, all bets are off when it comes to byte code running in the Java Virtual Machine. This paper will explore some of the implications of this curious lack of coherence between Java source code and byte code. It will also illustrate how easy it is to alter Java class files for malicious purposes.