Air-gaps, the technologies that large entities use to protect their most valuable information, was once considered impermeable since the data would be online. But now, Ben-Gurion University researchers in Israel have found a way to side-step the system, Bloomberg reported on Wednesday.

A popular computer virus is installed in a computer, then a hacker can manipulate the PC into sending information that can be accessed wirelessly by a mobile phone in another room. 

This isn't run-of-the-mill hackings of retailers or Gmail passwords, and would be used for cyber-espionage missions when very important secrets are at stake.

"The scenario is that you go to a secure facility and leave your cell phone at the entrance," said Dudu Mimran, chief technology officer at Ben-Gurion's cybersecurity labs. "The virus will send the data to your phone."

Military defense, sensitive and highly important infrastructure and medical equipment are usually kept separate from the internet. The discovery has sparked debate on air-gap effectiveness and if technology is moving passed them. The lab's YouTube channel has more than 100,000 views across its videos.

The research team has not yet found a way to tighten security against a hack, except to store equipment in metal enclosures or build walls that would interrupt radio frequencies so no data could be exchanged.

The first step would be installing a virus on the computer, which would require someone plugging in a virus-ridden USB stick into the hardware. The virus then makes the computer send signals over the display cable that can be received by cell phones in range.