A security researcher has found a backdoor in firmware used in a number of D-Link routers that could enable a hacker to alter the settings of the device.
The vulnerability was discovered by security researcher Craig Heffner. According to Heffner, if the user agent string of the user's web browser is xmlset_roodkcableoj28840ybtide, it is possible to access the web interface without any authentication and change the device settings. If an attacker can access a router's settings, it may be possible for them to manipulate and read the victim's Web traffic.
"A quick Google for the “xmlset_roodkcableoj28840ybtide” string turns up only a single Russian forum post from a few years ago, which notes that this is an “interesting line” inside the /bin/webs binary," he wrote. "I’d have to agree."
Heffner speculated that the backdoor may have been put in by developers in order to perform updates remotely.
"My guess is that the developers realized that some programs/services needed to be able to change the device’s settings automatically; realizing that the web server already had all the code to change these settings, they decided to just send requests to the web server whenever they needed to change something," he wrote. "The only problem was that the web server required a username and password, which the end user could change."
D-Link did not respond to a request for comment. However, in a statement online, D-Link said it is "proactively working with the sources of these reports" and is reviewing its entire product line to ensure any vulnerabilities discovered are addressed.
The company suggested users make sure remote access to the router is disabled (which is done by default) and ignore any unsolicited emails that relate to security vulnerabilities and urge them to take action.
The company also told BBC that a fix would be available by the end of October.
The affected models are believed to include DIR-100, DI-524, DI-524UP, DI-604S, DI-604UP, DI-604+, TM-G5240 and the DIR-615. Planex uses the same firmware in its BRL-04UR and BRL-04CW routers as well.