A typical office scanner can be infiltrated and a company’s network compromised using different light sources, according to a new paper by researchers from Ben-Gurion University of the Negev and the Weizmann Institute of Science.

“In this research, we demonstrated how to use a laser or smart bulb to establish a covert channel between an outside attacker and malware installed on a networked computer,” says lead author Ben Nassi, a graduate student in the BGU Department of Software and Information Systems Engineering as well as a researcher at the BGU Cyber Security Research Center (CSRC). “A scanner with the lid left open is sensitive to changes in the surrounding light and might be used as a back door into a company’s network.”

The researchers conducted several demonstrations to transmit a message into computers connected to a flatbed scanner. Using direct laser light sources up to a half-mile (900 meters) away, as well as on a drone outside their office building, the researchers successfully sent a message to trigger malware through the scanner.

In another demonstration, the researchers used a Galaxy 4 Smartphone to hijack a smart lightbulb (using radio signals) in the same room as the scanner. Using a program they wrote, they manipulated the smart bulb to emit pulsating light that delivered the triggering message in only seconds.

To mitigate this vulnerability, the researchers recommend organizations connect a scanner to the network through a proxy server — a computer that acts as an intermediary — which would prevent establishing a covert channel. This might be considered an extreme solution, however, since it also limits printing and faxing remotely on all-in-one devices.

“We believe this study will increase the awareness to this threat and result in secured protocols for scanning that will prevent an attacker from establishing such a covert channel through an external light source, smart bulb, TV, or other IoT (Internet of Things) device,” Nassi says.

Learn more: Scanners Can Be Hijacked to Perpetrate Cyberattacks