Researchers once again hack a Tesla Model S key fob

Owners of one Tesla model should maybe stop relying on just their key fob to unlock their car.

Researchers at Belgium university KU Leuven have reported that they’ve again successfully bypassed the keyless entry system of a Tesla Model S. 

The team first announced their ability to unlock a Model S with a cloned key fob last September. But, on Tuesday, the university’s Lennert Wouters presented evidence that they had managed to exploit a bug that bypassed Tesla’s patch of that initial weakness, again allowing access to a locked Model S. 

According to Wouters, it’s a configuration bug in the encryption of the key fob, which is produced by electronics company Pektron, that would allow a hacker to crack the code by breaking only a little bit more sweat than previously required. 

Reports Wired: 

Despite Tesla and Pektron’s upgrade from easily broken 40-bit encryption in the previous versions to far more secure 80-bit encryption in the newer key fobs—a doubling of the key length that ought to have made cracking the encryption about a trillion times harder—the bug allows hackers to reduce the problem to simply cracking two 40-bit keys. That shortcut makes finding the key only twice as hard as before.

Tesla told Wired that there’s no evidence that anyone has successfully used this hack to steal a Model S (the hack doesn’t affect other models since they use different key fobs). The company has already rolled out an easy-to-implement software update that fixes the issue and wirelessly updates the key fob in just a few minutes.

A spokesperson for Tesla told Mashable via email:

“While nothing can prevent against all vehicle thefts, Tesla has deployed several security enhancements, such as PIN to Drive, that makes them much less likely to occur. Even though we are not aware of a single customer ever affected by the reported issue, and enabling PIN to Drive already prevents this from occurring, we’ve begun to release an over-the-air software update (part of 2019.32) that addresses this researcher’s findings and allows certain Model S owners to update their key fobs inside their car in less than 2 minutes. We believe that neither of these options would be possible for any other automaker to release to existing owners, given our unique ability to roll out over-the-air updates that improve the functionality and security of our cars and key fobs.”

Additionally, Tesla’s PIN-code-to-drive feature, once enabled by the driver, can prevent this sort of theft from occurring by allowing the driver to set a four-digit code that must be entered before the car can be driven. 

It’s not the first time a Tesla has been at the center of fob vulnerabilities. A video that circulated in the fall of 2018 purports to show a thief using a relay attack to steal a Model S. As we reported then, the thieves amplified “the signal from the car owner’s key fob (located inside his home) in order to trick the vehicle into thinking the fob was present.”

And yet another video claiming to show a similar relay attack theft was shared by Business Insider earlier this month. 

To be fair, as Jalopnik notes, this sort of relay attack isn’t unique to Tesla; it’s a vulnerability that affects just about any car that utilizes a key fob. to protect your car from such a relay attack back in 2017. 

Tesla’s popularity and name-recognition just brings more attention even as the Model S is one of the least-stolen cars, according to one study. Disabling Tesla’s “passive entry” feature should prevent such a relay attack and its Sentry Mode offers another layer of security.

And, like the other theft attempts, these can be prevented by the added protection layer that comes with the PIN-to-drive feature which you should definitely enable, lest you allow your really, really expensive new ride to fall prey to some wily thieves. 

UPDATE: Aug. 28, 2019, 1:55 p.m. EDT Updated to include a statement from a Tesla spokesperson, clarifying the affected models, and providing additional information about Tesla secruity.