Air-gapped systems, which are isolated from the Internet and are not connected to other systems that are connected to the Internet, are used in situations that demand high security because they make siphoning data from them difficult.
Air-gapped systems are used in classified military networks, the payment networks that process credit and debit card transactions for retailers, and in industrial control systems that operate critical infrastructure. Even journalists use them to prevent intruders from remotely accessing sensitive data. To siphon data from an air-gapped system generally requires physical access to the machine, using removable media like a USB flash drive or a firewire cable to connect the air-gapped system directly to another computer.
But security researchers at Ben Gurion University in Israel have found a way to retrieve data from an air-gapped computer using only heat emissions and a computer’s built-in thermal sensors. The method would allow attackers to surreptitiously siphon passwords or security keys from a protected system and transmit the data to an internet-connected system that’s in close proximity and that the attackers control. They could also use the internet-connected system to send malicious commands to the air-gapped system using the same heat and sensor technique.
In a video demonstration produced by the researchers, they show how they were able to send a command from one computer to an adjacent air-gapped machine to re-position a missile-launch toy the air-gapped system controlled.
The proof-of-concept attack requires both systems to first be compromised with malware. And currently, the attack allows for just eight bits of data to be reliably transmitted over an hour—a rate that is sufficient for an attacker to transmit brief commands or siphon a password or secret key but not large amounts of data. It also works only if the air-gapped system is within 40 centimeters (about 15 inches) from the other computer the attackers control. But the researchers, at Ben Gurion’s Cyber Security Labs, note that this latter scenario is not uncommon, because air-gapped systems often sit on desktops alongside Internet-connected ones so that workers can easily access both.
The method was developed by Mordechai Guri in a project overseen by his adviser Yuval Elovici. The research represents just a first step says Dudu Mimran, chief technology officer at the lab, who says they plan to present their findings at a security conference in Tel Aviv next week and release a paper describing their work later on.
“We expect this pioneering work to serve as the foundation of subsequent research, which will focus on various aspects of the thermal channel and improve its capabilities,” the researchers note in their paper. With additional research, they say they may be able to increase the distance between the two communicating computers and the speed of data transfer between them.
In their video demonstration, they used one computer tower to initiate a command to an adjacent computer tower representing an air-gapped system. But future research might involve using the so-called internet of things as an attack vector—an internet-connected heating and air conditioning system or a fax machine that’s remotely accessible and can be compromised to emit controlled fluctuations in temperature.
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Wed Mar 25, 2015 1:43 pm
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