LAS VEGAS—If you’re the proud owner of an all-electric vehicle, you likely invested in a home charger. However, since modern cars are well-defended against hacking, criminals have turned to hacking the chargers.
At last year’s Black Hat, we learned that hackers could meddle with your charging schedule, choke down the charging speed, or tweak the billing. None of that would be fun, but it doesn’t compare to this year’s conference, where researchers from Trend Micro showcased how they could do physical damage to your charger, right up to burning your house down.
Jonathan Andersson, security research manager at Trend Micro, started with a shoutout to Pwn2Own automotive, a hacking contest sponsored by Trend Micro’s Zero Day Initiative devoted to demonstrating security vulnerabilities in cars and related tech. After reviewing past winners, he noted that the bugs they found were all very simple.
“When you take these devices apart, they typically have a main CPU that runs the GUI,” Andersson said. “Sometimes there’s a second processor for power switching and measurement. There are also a lot of devices and peripherals that contribute to quite a large attack surface.”
In short, EV chargers aren’t currently designed with security in mind.
With Great Power Comes Great Overheating
Thanos Kaliyanakis, also a Trend Micro researcher, said his team first performed baseline testing on out-of-the-box unmodified EV chargers, all of which correctly prevented overheating. The team then made a small modification to disable internal protection against overheating and tested again, looking for any secondary safety systems.
“To achieve the task, we needed a way to load the EV chargers with maximum power and pull as much current as possible,” said Kaliyanakis. “We used a bank of heaters to draw various amounts of current during testing.”
At first, I thought we’d hear about how a hacker across the world could reach into your EV charger and set it on fire. Thankfully, that’s not the case. The hack only works on a charger that’s had a small physical modification or is defective.
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Even so, the results, as demonstrated in a clip reel of all the tests, were nothing short of alarming. In every case, the cables overheated. Some spewed flames, including bits of molten copper. Some released flammable gases into the air, which then ignited. One melted the cord holder off the wall.
“Any cable that didn’t fail violently still failed by melting,” said Andersson. “If the melting cable shorts power through the signal channels, your EV could be damaged.” He noted that overheating the devices to failure took anywhere from an hour to 5.5 hours.
How to Protect Your EV Right Now
Andersson pointed out that you can’t expect a circuit breaker to save your EV charger in this scenario—not unless you purchase a high-end one rated for 80 amps.
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“Don’t mount the cable under the charger, or under anything flammable,” he advised. “Don’t keep the cable coiled while charging. The manufacturer may recommend wrapping the cord around the charger—don’t do that. A shorter cable is safer.”
Andersson encouraged EV charger vendors to “own this problem and fix it.” He noted that new but poor-quality chargers show up for sale every day, with the same-old bugs.
Andersson showed a simple circuit diagram for a modified charger that would be immune to the overheating problem reported here, and urged EV manufacturers to embrace it.
As for your trusty charger in your garage, it probably won’t explode into a ball of fire. As noted, the attack described here only works on a modified (or defective) charger. But it’s still not a bad idea to get a shorter cable.
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About Neil J. Rubenking
Principal Writer, Security
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