A cyber attacker could take control of your entire organization by simply obtaining a fax number.

That’s according to new research by Check Point Software Technologies that shows how organizations and individuals could be hacked via their fax machines with newly discovered vulnerabilities in the communication protocols used in tens of millions of fax devices globally.

The findings were presented Sunday at the Def Con hackers conference.

The research demonstrated vulnerabilities in the HP Officejet Pro All-in-One fax printers. The same protocols also are used by many other vendors’ faxes and multi-function printers, and in online fax services such as fax2email, “so it is likely that these are also vulnerable to attack by the same method,” according to Check Point.

Following discovery of the vulnerabilities, Check Point shared the findings with HP, which developed a software patch for its printers.

There are more than 45 million fax machines in use in businesses globally, with 17 billion faxes sent every year. It is still widely used in several Industry sectors such as health care, legal, banking and real estate, where organizations store and process large amounts of sensitive personal data, according to Check Point.

Check Point’s Yaniv Balmas

“Many companies may not even be aware they have a fax machine connected to their network, but fax capability is built into many multi-function office and home printers,” said Yaniv Balmas, Check Point’s group manager of security research. “This groundbreaking research shows how these overlooked devices can be targeted by criminals and used to take over networks to breach data or disrupt operations It’s critical that organizations protect themselves against these possible attacks by updating their fax machines with the latest patches and separating them from other devices on their networks”

Once an attacker obtains an organization’s fax number, which is easily obtainable from corporate websites, the attacker sends a specially created image file by fax to the target. The vulnerabilities allow malware, such as ransomware, crypto-miners or spyware, to be coded into the image file, which the fax machine decodes and uploads to its memory. The malware then can potentially breach sensitive data or cause disruption by spreading across any networks to which the fax machine is connected, according to Check Point.

To minimize the security risk, Check Point said organizations should check for available firmware updates for their fax devices and apply them. Businesses also are urged to place fax devices on a secure network segment separated from applications and servers that carry sensitive information. That will limit the ability of malware to spread across networks.