Manufacturers often design printed circuit boards for their products but lack manufacturing capability, so they outsource production. Experts warn that these factories are a point of vulnerability where an attacker could insert malicious features, known as Trojan attacks. Such attacks could steal sensitive data or crash a device when triggered.
Only one Trojan attack has ever been reported in the wild, , but later denied by all companies mentioned. at the University of Cambridge says that no firm evidence has ever been found to prove such an attack occurred, but he believes the concept to be feasible.
Circuit boards are so complex that they can’t be designed or analysed fully by humans, and require automated tools to engineer. “When you look at what comes out, it’s just spaghetti,” he says. “You can’t see any structure in there. So it’s very difficult to know whether the structure that came out is what you asked for, or whether there’s anything lurking in there that you didn’t ask for.”
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at Washington University in St. Louis, Missouri, and his colleagues created a test called PDNPulse that analyses the power consumption of a printed circuit board to watch for tiny variations in what they call the “fingerprint” of power consumption, based on measurement at several points. When compared to a device known to be safe, these can reveal tampering.
The team says that the power consumption characteristics are inevitably affected by modifications to the circuit board, no matter how minuscule. In tests, the researchers were able to detect Trojan changes on a variety of circuit boards with 100 per cent accuracy. The team declined to comment on the work.
at Queen’s University Belfast, UK, says such research is vital. “We do know that governance, governments and companies take this type of research seriously, and that the kinds of threats that are being pitched as possible are certainly feasible,” she says. “And I think from that point of view, yes, research needs to be done to kind of consider what is truly possible.”
But O’Neill warned that the technique wasn’t a silver bullet to catch any attack, because a so-called “golden model” of circuit board known to be free of malicious features is needed for comparison, and most companies have no capacity to make such circuit boards, even in small numbers.
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