D-Link routers reportedly have issue that makes them susceptible to unauthorized backdoor access. A researcher demonstrated the presence of a backdoor within some DLink routers that allows an attacker to access the administration web interface of network devices without any authentication and view/change its settings. The DIR-100 revA.13 router is among the devices affected by the issue. The vulnerability is how it can be exploited, anyone connected to the router, whether it’s through Ethernet or Wi -Fi, can simply set their browser’s user agent string to a specific codeword.
Source: https://thehackernews.com/2013/10/unauthorized-access-backdoor-found-in-d.html