WHEN YOU THINK of a standard hacker toolkit, software vulnerabilities and malware come to mind. But a pair of researchers are testing a different type of instrument: a physical tool that can break into devices with a wave of your hand.
At the recent REcon computer security conference, Red Balloon Security founder Ang Cui and research scientist Rick Housley presented a new approach to hacking a processor that uses electromagnetic pulses to produce specific glitches in hardware. By disrupting normal activity at precise intervals, the technique can defeat the Secure Boot protection that keeps processors from running untrusted code.
Researchers have experimented with “fault injection attacks”—hacks that cause a strategic glitch, which in turn triggers abnormal, exploitable computer behavior—for decades. Those attacks, though, typically require physical access to a target’s components.
“The advantage of this technique is that it’s physically noninvasive. You don’t have to touch the device, and you don’t leave any physical marks behind,” Cui says. “There’s no exchange of data at the electromagnetic pulse stage, so this would never be caught by a firewall.”
Red Balloon specializes in internet-of-things-intrusion defense; think of it as antivirus software for IoT. But the company has run into problems putting its security tool on IoT devices guarded by Secure Boot. Red Balloon’s products don’t undermine this safeguard; the company works with vendors to make its software compatible. But the dilemma got Cui and Housley interested in the theoretical question of whether a fault-injection attack could circumvent Secure Boot on locked-down IoT devices.
They started experimenting with the Cisco 8861 VoIP phone model that they had tried and failed to equip with their security product. (Cui also has a history of hacking Cisco phones.) The two found that if they poked the phone’s flash memory with a charged wire at the right moment while it booted up, they could cause a glitch that stopped the boot process. Instead, the phone surfaced access to a command-line interface that Cisco normally uses for debugging. Consumers are never supposed to see it.