This work was sponsored by the University of Richmond, School of Arts & Sciences, Department of Math and Computer Science.

The increased use of the World Wide Web and JavaScript as a scripting language for Web pages have made JavaScript a popular attack vector for infecting users' machines with malware. Additionally, attackers often obfuscate their code to avoid detection, which heightens the challenge and complexity of automated defense systems. We present two analyses of malicious scripts and suggest how they could be extended into intrusion detection systems. For our analyses we use a sample of deobfuscated malicious and benign scripts collected from actual Web sites.

Highly nonlinear Boolean functions play a central role in the design and security analysis of high speed stream cyphers and block cyphers. We focus on analyzing the structure of Boolean functions that exhibit high second order nonlinearity. We commence with a theoretical overview of Boolean functions and Reed- Muller codes. We then introduce a new equivalence relation, 2-equivalence, for which we prove a number of important properties. Finally, we analyze the second order nonlinearity of concatenations of two Boolean functions.