Hackers using cheap wireless devices pose a threat to millions of cars equipped with Volkswagen’s keyless entry system, according to a study from the University of Birmingham. Scheduled for presentation Friday at the USENIX security conference in Austin, Texas, the study shows that thieves can use a simple wireless device to unlock the doors of millions of cars remotely, essentially by cloning the remote control that wirelessly secures a car door lock. A second hack involves recovering the cryptographic key by attacking the rolling code scheme.