In common with many other vendors, TP-Link, one of the world's biggest sellers of Wi-Fi access points and home routers, has a domain name that owners of the hardware can use to quickly get to their router's configuration page. Unlike most other vendors, however, it appears that TP-Link has failed to renew its registration for the domain, leaving it available for anyone to buy. Any owner of the domain could feasibly use it for fake administration pages to phish credentials or upload bogus firmware. This omission was spotted by Amitay Dan, CEO of Cybermoon, and posted to the Bugtraq mailing list last week.

Two domain names used by TP-Link appear to be affected. tplinklogin-dot-net was used, according to TP-Link, on devices sold until 2014. On initial setup, while the router's Internet connection is still offline, the domain name will be trapped automatically and correctly send users to the router's configuration page. But subsequent visits to the configuration page can use the real Internet DNS system to resolve the address, and hence those routers are susceptible to being hijacked. A second TP-Link domain name, tplinkextender-dot-net, was used by TP-Link wireless range extenders and is similarly vulnerable.

Together, these domain names appear to be quite busy; estimates based on Alexa's ranking suggest that tplinklogin-dot-net sees about 4.4 million visits per month, with another 800,000 for tplinkextender-dot-net. It's not known who the new owner of the domains is, but Dan tweeted that domain name brokers are offering the more popular of the two for $2.5 million. This high price tag is perhaps why TP-Link has declined to buy the name back.

New TP-Link devices use tplinkwifi-dot-net and tplinkrepeater-dot-net as their configuration URLs for access points and range extenders, respectively. Dan says that TP-Link stopped communicating with him after changing references to the bad domain names from their manuals to use the new domain names as a partial fix. This does nothing to alter the stickers found on the backs or bottoms of affected devices that continue to reference the unregistered domains. There are also still references to the old domain names on TP-Link's website.