WHY THIS MATTERS IN BRIEF
4D printing lets us create morphing products with special on demand properties which could be sabotaged to cause deadly failures.
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4D printing, a relatively new advanced manufacturing technology that prints parts and products that change shape when exposed to different stimuli, such as heat or water, and which is already being lined up by NASA to print and assemble space stations in orbit, as well as 4D print new materials, robots, and replacement human organs for children, could be vulnerable to a completely new kind of custom attack security researchers have warned.
At a recent conference Tuan Le at Rutgers University in the US and his colleagues warned that as 4D printing starts going mainstream companies should seriously consider analysing the technology’s security. They then went on to suggest that using 4D printing in critical applications, such as aircraft and medical devices, could open the door for malicious attackers to cause “catastrophic failures.”
The researchers claim that a hacker who gains access to a computer designing parts or the printer itself could tweak designs.
“The attacker can compromise the controller software that is in charge of the selection of printing materials. This would enable the attacker to implement the attack and embed the smart material in pre-determined spots for delayed activation,” they wrote.
For example, aircraft propellers could be altered so that they change pitch angle at a certain temperature, potentially causing a fatal crash. In experiments, a propeller with malicious changes produced 42g of thrust at 25 per cent throttle, while the original design produced 55.8g. Yet to the naked eye both propellers appeared identical.
Alternatively, face masks could be modified so that when they are cleaned with water, a tiny channel is formed by dissolving material that allows air and viruses to pass through the filter.
To protect against these threats, the researchers say that CT scans can detect manipulations better than existing approaches. In tests, they found that scans lasting 30 minutes could distinguish hacked propellers from benign ones with 94.6 per cent accuracy.
“The digital machines doing that could be attacked in exactly the same way, with similar results,” he says. “Any digitally controlled manufacturing process for a complicated multi-part object is equally susceptible, and has been since the invention of computer numerically controlled machines almost 70 years ago.”
Bowyer says he is unaware of a single such attack in the real world though – yet.
“When things are made as one-offs for critical applications, they are rigorously tested. This would reveal the attack,” he says. “When things are made in bulk for critical applications, they are randomly sampled and the samples are rigorously tested. This would also reveal the attack. The sensing techniques that they have developed would probably be a lot more useful to tell when a printer had gone wrong, which is a much more likely eventuality than a deliberate attack.”
Meanwhille, Eujin Pei at Brunel University London says that tiny changes to printing instructions can change the property of even traditional 3D printed parts, but agrees that the best defence is good quality control.
“You need to undergo stringent tests for this type of application,” he says.