Experts from the U.S. Department of Homeland Security (DHS) deliberately hacked a Boeing 757 remotely in just two days without the pilots even knowing about it.

The team was able to access and gain control of the plane’s systems using radio frequency communications.

The hacking was done at an Atlantic City, New Jersey airport last year as part of a test. DHS acquired the Boeing 757 in September 2016. Since the test was apparently classified, details have not been released.

A member of the team, though, said no one ever touched the airplane — there was no insider threat. They “stood off” using typical items that could get through security. As a result, they were able to gain access to the systems on the plane.

The DHS artificial environment and risk reduction measures were already in place. A Boeing employee was even present when the aircraft was hacked.

Findings of the test

The confidential test revealed that there are no cyber vulnerabilities in the 757 or any other Boeing aircraft. Also, the test does not show a major threat to airlines since the hacking involved attack methods on older aircrafts with less advanced systems.

The reason the DHS test was done was reportedly due to a 2015 incident involving hacker Chris Robert. He was arrested after admitting to hacking commercial airplanes almost 20 times while in flight.

Hackers are also breaking into the medical field. Earlier this year, pacemakers were the target.