At the BlackHat conference in Las Vegas, Battelle security researcher Christopher Domas revealed a hidden security flaw that affected Intel processors for 16 years. The first flawed chips appeared in 1995, and the problem wasn't fixed until the 2011 crop of new processors that included the Sandy Bridge series.

The strange problem occurs at such a deep level of the hardware architecture that it is unstoppable and undetectable by the operating system. Intel processors have a privilege ring architecture that defines the level of privilege available to a process. As most developers and power users know, the kernel occupies Ring 0, usermode applications live at Ring 3, and device drivers fall somewhere in between. Far lesser known are the mysterious rings inside of Ring 0. Ring -1 is the hypervisor ring, which manages the operating systems running at Ring 0, and below that, the murky Ring -2 is home to Intel's System Management Mode software. This innermost ring is loaded by the system firmware, and it is effectively untouched by the rest of the system. The bug that affected Intel processors for 16 years allows privilege escalation code to run at Ring -2, where it was invisible to the rest of the system.

Users with older PCs should watch for more news on this problem, but it doesn't look like a quick fix will appear anytime soon, and now that the flaw has been published in the press, it is only a matter of time before intruders exploit it. Linux users better not bet on that natural security of Linux systems to get you through this one: The operating system is just another app when you're down in Ring -2.