A sizeable proportion of 100 million Volkswagen Group cars sold since 1995 can be unlocked remotely by hackers, a team of researchers has said.
The problem affects a range of vehicles manufactured between 1995 and 2016 – including VWs and models from the company’s Audi, Seat and Skoda brands.
A homemade radio costing about £30 is the only hardware an attacker requires.
Volkswagen said it was working with the researchers and added that several new vehicles were unaffected by the issue.
Two separate attacks affecting different models are described by researchers from the University of Birmingham and German security firm Kasper & Oswald.
With the second method, an older cryptographic scheme in some other brands was found to have a similar, albeit more complex vulnerability.
The team showed it was possible for a malicious hacker to spy on key fob signals to target cars via a cheap, homemade radio.
By cloning the digital keys, the researchers found they could then unlock a variety of VW Group vehicles.
This was possible because they were able to reverse engineer the keyless entry system in the affected models a process which yielded some master cryptographic keys.
Prior to publishing their research, the team behind the paper agreed with Volkswagen that some key pieces of information including the value of the master cryptographic keys – would not be made public.
“We were kind of shocked,” Timo Kasper at Kasper & Oswald told the BBC. “Millions of keys using the same secrets from a cryptography point of view, that’s a catastrophe.”