Learn about how the cutting-edge, free software Heads project detects BIOS and kernel tampering, all with keys under your control. Some of the earliest computer viruses attacked the boot sector—that bit of code at the beginning of the hard drive in the Master Boot Record that allowed you to boot into your operating system. The reasons for this have to do with stealth and persistence. Viruses on the filesystem itself would be erased if users re-installed their operating systems, but if they didn't erase the boot sector as part of the re-install process, boot sector viruses could stick around and re-infect the operating system.

There's an ongoing series of skirmishes between corporations who want to sell products that users don't fully control and the kernel developers who want users to be the highest authority. Sometimes these skirmishes manifest in the form of security patches intended to lock down the kernel. Do they lock down the kernel against outside attackers? Or do they lock down the kernel against change from anyone at all, including the user who owns the device?