It is not an attack which works over the net. The attacker has to be on the local network. It could be used to commandeer a wireless access point and allow an attacker to get unfettered access to local network resources which is messy. Eloi Vanderbeken posted details of the attack to Github. He found the backdoor when he was trying to get access to the administrative console of his family’s Linksys WAG200G wireless DSL gateway wirelessly. He wanted to limit how much bandwidth the others in the house were using, but had turned off wireless access to the administration web console and had forgotten his administrative password.
The router responded to messages over an unusual TCP port number: 32764. He downloaded a copy of the Linksys firmware and commenced reverse-engineering the binary MIPS code. What he found was a simple interface that allowed him to send commands to the router without being authenticated as the administrator.
Vanderbecken found that the interface allowed him to execute a number of commands directly against the router, including a command-line shell. Using the commands he discovered, he was able to write a script that allowed him to turn wireless access to administration on and reset the web password.