Is your PC secretly running nuclear simulations

Large-scale attacks on networked computers are typi-cally used to create zombie armies for propagating spam or launching DDoS attacks. But they can also be used to harvest immense computing power for use in running nuclear simulations or cryptanalysis attempts. We show that all major operating systems today (possibly except Mac OS X) are vulnerable to such attacks, due to a com-bination of how they account for CPU usage and how they prioritize competing processes. Specifically, we de-tail a “cheat ” attack, by which a non-privileged process can hijack a large percentage of the CPU cycles. More-over, in at least some of the systems, listing the active processes will erroneously show that the cheating pro-cess is not using any CPU resources at all, making it hard to detect the attack. This can also be a “desirable” feature for spyware designers. We also show that such vulnerabilities are actually quite simple to avoid, and we demonstrate this by implementing a patch for Linux 2.6.