Some Internet gateway devices commonly used by hotels and conference centers can easily be compromised by hackers, allowing them to launch a variety of attacks against guests accessing the Wi-Fi networks.

The affected devices, designed to manage visitor-based networks, are manufactured by a company called ANTlabs and are used by both cheap and luxury hotels around the world, according to researchers from security firm Cylance.

The researchers discovered that multiple ANTLabs InnGate models contained a misconfigured rsync service that listened on TCP port 873 and gave unauthenticated attackers full read and write access to the device file system.

Rsync is a utility used for file and directory synchronization between Linux systems, so it has file upload and download functionality. The tool supports authentication and can be limited to specific directories, but on the affected ANTLabs InnGate devices, it had been configured in an insecure manner by default.

“When an attacker gains full read and write access to a Linux file system, it’s trivial to then turn that into remote code execution,” Cylance researcher Brian Wallace said in a blog post. “The attacker could upload a backdoored version of nearly any executable on the system and then gain execution control, or simply add an additional user with root level access and a password known to the attacker. Once full file system access is obtained, the endpoint is at the mercy of the attacker.”

ANTlabs released patches Thursday to address the flaw, which is tracked as CVE-2015-0932. Fixes are available for several affected models: IG 3100 and 3101; InnGate 3.00 E-Series, 3.01 E-Series, 3.02 E-Series and 3.10 E-Series, and InnGate 3.01 G-Series and 3.10 G-Series.

Hotel networks are an attractive target for hackers. In November, researchers from Kaspersky Lab documented the activity of a cyberespionage group dubbed DarkHotel that targeted traveling corporate executives and entrepreneurs by compromising the networks of luxury hotels in the Asia-Pacific region.

The InnGate vulnerability could allow hackers to launch attacks against hotel Wi-Fi guests similar to those perpetrated by the DarkHotel group. With access to such a device attackers could monitor traffic that passes through it for sensitive information, they could replace files that users attempt to download from the Internet with malicious ones on the fly, they could strip connections of SSL encryption or downgrade their security, and much more.

“Given the level of access that this vulnerability offers to attackers, there is seemingly no limit to what they could do,” Wallace said.

In some cases, it’s not just hotel guests that are put at risk by this flaw, but the hotel’s entire business. The Cylance researchers found cases where the InnGate devices were integrated with property management systems (PMS), which are used by hotels to run many aspects of their business: reservations, sales, planning, human resources, payroll, maintenance, inventory and more.

Cylance found 277 vulnerable InnGate devices in 29 countries that can be directly attacked from the Internet. Many of them were located in the U.S.

“Listing those vulnerable devices at this time would be irresponsible and could result in a compromise of those networks,” Wallace said. “Take it from us that this issue affects hotel brands all up and down the spectrum of cost, from places we’ve never heard of to places that cost more per night than most apartments cost to rent for a month.”