ZyNOS

ZyNOS is the proprietary operating system used on network devices made by Zyxel Communications.^[1] The name is a contraction of Zyxel and Network Operating System (NOS).

Zyxel first introduced ZyNOS in 1998.^[2]

Zyxel released ZyNOS version 4.0 for their GS2200 series 24 and 48 port ethernet switches in April, 2012.^[3] It appears that versions differ between Zyxel products.

Web and/or command-line interface (CLI) depending on the device. Web access is accomplished by connecting an Ethernet cable between a PC and an open port on the device and entering the IP address of the device into the Web browser.^[4] An RS-232 serial console port is provided on some devices for CLI access, which is accomplished by using SSH or telnet.^[5]

Listed below are the categories that the CLI commands are grouped by.^[6]

The Web Configurator is divided into the following categories:^[7][4]

• basic settings
• advanced application
• IP application
• management

As of January 2014 a ZyNOS ROM-0 vulnerability has been identified.^[8] This vulnerability allowed attacker to download router's configuration (ROM-0 file) without any type of authentication required. Such configuration file can be later decompressed^[9][10] to expose router's administrator password, ISP password, wireless password etc.

As of March 2014^[update], Danish computer security company Secunia reports no unpatched advisories or vulnerabilities on ZyNOS version 4.x.^[11]

As of March 2014^[update], Secunia reports seven advisories and six vulnerabilities on ZyNOS version 3.x. Five advisories are unpatched; Secunia rates the most severe unpatched advisory as less critical.^[12]

As of January 2015^[update], a DNS vulnerability has been found in certain ZyNOS firmware versions. The versions that are affected have not been narrowed down. The attack can be done from a remote location regardless if the user interface is accessible from the outside of a LAN.^[13]