Netgear Nighthawk R6700v3 routers running the latest firmware are affected by multiple vulnerabilities. Details of the flaws were disclosed last week by Tenable after the vendor failed to release patches. The most important of these security defects results in an authenticated attacker being able to inject commands that would be executed when the device checks for updates. Tracked as CVE-2021-20173, the issue exists because unsanitized input is being sent to system() calls in the upnpd binary. The attacker can send requests from the SOAP interface to force update checks and trigger the execution of commands. Furthermore, Tenable’s researchers discovered that communication to and from the device’s web and SOAP interfaces is not encrypted, meaning that sensitive information – such as usernames and passwords – is transmitted in cleartext. The issues were assigned CVE identifiers CVE-2021-20174 and CVE-2021-20175, respectively. Tenable also noticed that the device stores usernames and passwords in plaintext, including the admin password. This issue is tracked as CVE-2021-45077. Another identified vulnerability (CVE-2021-23147) could allow an attacker with physical access to the device to connect to the UART port via a serial connection and run commands as root without authentication. “We recommend disabling this UART console for production runs, or at least enforcing the same password mechanisms used for other functionality in the device (such as the web UI),” Tenable says. Because encryption routines are hardcoded on the device (CVE-2021-45732), although configuration backups are encrypted, a user can leverage publicly available tools to extract the configuration and reconfigure settings that should not be changed.
Users of Netgear Nighthawk R6700v3 routers should upgrade from the firmware version 22.214.171.124 as soon as a version that fixes these vulnerabilities becomes available. The vulnerability where a user can connect with the UART port and run commands as root without authentication is fairly common in embedded devices, and isn’t a cause for quite as much concern as long as there is good physical security around where the routers are stored.