In one of more impressive hacks in recent memory, researchers have devised an attack that exploits physical weaknesses in certain types of DDR memory chips to elevate the system rights of untrusted users of Intel-compatible PCs running Linux.
The technique, outlined in a blog post published Monday by Google's Project Zero security initiative, works by reversing individual bits of data stored in DDR3 chip modules known as DIMMs. Last year, scientists proved that such "bit flipping" could be accomplished by repeatedly accessing small regions of memory, a feat that—like a magician who transforms a horse into a rabbit—allowed them to change the value of contents stored in computer memory. The research unveiled Monday showed how to fold such bit flipping into an actual attack.
"The thing that is really impressive to me in what we see here is in some sense an analog- and manufacturing-related bug that is potentially exploitable in software," David Kanter, senior editor of the Microprocessor Report, told Ars. "This is reaching down into the underlying physics of the hardware, which from my standpoint is cool to see. In essence, the exploit is jumping several layers of the stack."