Some routers found to be listening on undocumented port

In a period of time where the NSA has been accused of intercepting data from PCs and online networks, there's now a newly discovered flaw in many routers that could allow people to remotely access the hardware to gain admin access, among other things.

The Netgear DGN2000 is one of the routers found to be listening in on the port 32764.

A few days ago, a known hacker named Eloi Vanderbeken posted up a note on GitHub. He wrote about his discovery that his Linksys WAG200G wireless DSL gateway was listening on the undocumented TCP port 32764. He later found that the port was open on a number of other routers from Linksys, Netgear, Cisco and others. While some of these products have the port open just on their local network, several of them are exposed when connected to the Internet.

So why do so many of these routers have this previously unknown port? It's not currently known, but the GHacks.net website offers up several ways to find out if a home or work router has this undocumented port active.

If the port is found, the site has a number of recommendations to close this vulnerability. They include adding a rule to the router's firewall to block the 32764 port or downloading an open source firmware for the hardware. Of course, the easiest thing to do is simply replace the router with one that is not listening in on the port.

Source: GitHub and GHacks | Image via Netgear

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I guess these are for "remote management and diagnostics".

Virgin Media's routers have a similar feature, but it's only available over a cable connection, not the internet.

Likewise, all BT infinity modems (NOT the homehub) have BT agent built in, I flashed mine with an alternative firmware and have it disabled.

francescob said,
How comes they found this out now? It's not like portscans are really that rare...

From what I understand the port number is outside the range of ports defined by the IANA, so unless somebody knew to plug this port number into their software, most things wouldn't even look for it.

You have to use their python script which initiates a specific way of interfacing with the router and then issue commands from there. You can't just use your browser to connect to the port.

Made a post a week ago about this, also other routers are affected by various backdoors:

Speedport: http://www.heise.de/netze/meld...elekom-Routern-1558346.html
D-Link: http://www.devttys0.com/2013/1...ineering-a-d-link-backdoor/
TP-Link: http://sekurak.pl/tp-link-httptftp-backdoor/
Cisco: https://web.archive.org/web/20.../cisco-sa-20040407-username

Not to mention counterfeit hardware with who knows what: http://www.mercurynews.com/bus...r-arrested-after-indictment

I highly recommend installing DD-WRT or OpenWRT. I won't use any routers that have original firmware because of stuff like this, it's ridiculous how incompetent these companies are.

You could brick your router and void your warranty but I think the benefits outweigh the risk. Use at your own risk: http://dd-wrt.com/site/support/router-database

Edited by Geezy, Jan 6 2014, 9:00pm :

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