An Israeli cybersecurity firm is raising fresh concerns about hackers taking control of moving cars, remotely shutting down an engine with the help of a smartphone app, a Bluetooth connection and a type of device commonly plugged into ports located under vehicle dashboards.

Argus Cyber Security Ltd. said Thursday it was able to use a so-called dongle, a device often installed by insurance companies to monitor driving patterns or by owners wanting in-vehicle Wi-Fi, to crack into a vehicle’s internal communication system. The firm, well known in automotive circles, triggered a signal meant to disable the fuel pump, something that normally would happen only after a collision.

Argus didn’t disclose the model of car it hacked, noting most cars on the road have a diagnostic port designed for a dongle device. The breach is the latest in a series of high-profile hacks, including an incident two years ago staged by two security researchers who controlled a Jeep Cherokee via a wireless internet connection.

Cars are increasingly connected to external communications, prompting computer experts to exploit holes in firewalls installed by auto makers to separate media features from more critical functions, such as engines, transmissions or brakes. With more than 250 million vehicles on U.S. roads, industry executives have said beefing up controls is a priority.

“These firewalls are really new and immature in their security measures,” Ami Shalev, Argus research team leader, said in an interview.