Malware writers constantly seek new methods to obfuscate their code so as to evade detection by virus scanners. Two code-armoring techniques that pose significant challenges to existing malicious-code detection and analysis systems are unpacking and run-time polymorphism. In this paper, we demonstrate how malware can increase its robustness against detection by taking advantage of the ubiquitous Graphics Processing Unit. We have designed and implemented unpacking and run-time polymorphism for a GPU, and tested them using existing graphics hardware. We also discuss how upcoming GPU features can be utilized to build even more robust, evasive, and functional malware.