Feeds

Tenda seals shut router backdoor found by D-Link hole-prober

Shut the back door!

SANS - Survey on application security programs

Chinese networking manufacturer Tenda has issued a fix that seals up a recently discovered backdoor in its wireless router kit.

Craig Heffner, the same researcher who uncovered a backdoor in routers from D-Link, uncovered more secret functionality that ships with Tenda's products.

Heffner discovered the flaw after unpacking firmware updates for Tenda's networking kit and locating suspicious code.

Attackers could take over the router and execute commands simply by sending a UDP packet with a special string, as explained in a detailed advisory.

"The backdoor only listens on the LAN, thus it is not exploitable from the WAN," Heffner explains. "However, it is exploitable over the wireless network, which has WPS enabled by default with no brute force rate limiting. My shiny new ReaverPro box made relatively short work of cracking WPS, providing access to the WLAN and a subsequent root shell on the router.'

Heffner warned that the backdoor was present on Tenda’s W302R and W330R router models as as well as re-branded models, such as the Medialink MWN-WAPR150N, because all share the same exploitable functionality (specifically a “w302r_mfg” magic packet string in a modified GoAhead webserver) that ships with the products.

Attackers could gain unauthenticated access to the routers’ administrative interfaces through its built-in web server on all affected models, provided they had first managed to hop onto the same network as their intended victim.

Target Components, which distributes Tenda's products in the UK, acknowledged the problem while crediting Tenda for developing a fix in just two days.

The company had released a software update that closes the backdoor on the three affected models. Target added that, contrary to fears expressed by other security researchers in they wake of Heffner's discovery, the backdoor problem was restricted to three models of Tenda-manufactured kit.

In a statement, Tenda apologised to its customers and said: “We promise that no other lines of Tenda have the same bugs after all lines were detected systematically by our engineers.”

Tenda's notice (in less-than-perfect but broadly understandable English, key extract below) also plays down the significance of the whole security flap.

It was also verified by our engineers that the bug will not make your network system be visited via internet by strangers, so we can promise that there is no big security problem occurred. However, we would suggest that all the SME users who use those two lines upgrade them immediately just in case of further security problems.

The relevant security patches can be found via links within Tenda's advisory here.

We passed on Tenda's advisory to Heffner but are yet to hear from him. Thus there's no confirmation that the fix released by Tenda actually does what it says on the tin.

Earlier this month Heffner discovered a similar backdoor on a range of router kit from D-Link. In response, D-Link promised to close its routers' backdoors by Halloween (31 October).

Pending the availability of a fix, users of the vulnerable kit are advised to disable remote access to their routers and make sure their wireless networks are secure. ®

High performance access to file storage

More from The Register

next story
Obama allows NSA to exploit 0-days: report
If the spooks say they need it, they get it
Samsung Galaxy S5 fingerprint scanner hacked in just 4 DAYS
Sammy's newbie cooked slower than iPhone, also costs more to build
Putin tells Snowden: Russia conducts no US-style mass surveillance
Gov't is too broke for that, Russian prez says
Snowden-inspired crypto-email service Lavaboom launches
German service pays tribute to Lavabit
Mounties always get their man: Heartbleed 'hacker', 19, CUFFED
Canadian teen accused of raiding tax computers using OpenSSL bug
One year on: diplomatic fail as Chinese APT gangs get back to work
Mandiant says past 12 months shows Beijing won't call off its hackers
Call of Duty 'fragged using OpenSSL's Heartbleed exploit'
So it begins ... or maybe not, says one analyst
prev story

Whitepapers

Top three mobile application threats
Learn about three of the top mobile application security threats facing businesses today and recommendations on how to mitigate the risk.
Combat fraud and increase customer satisfaction
Based on their experience using HP ArcSight Enterprise Security Manager for IT security operations, Finansbank moved to HP ArcSight ESM for fraud management.
The benefits of software based PBX
Why you should break free from your proprietary PBX and how to leverage your existing server hardware.
Five 3D headsets to be won!
We were so impressed by the Durovis Dive headset we’ve asked the company to give some away to Reg readers.
SANS - Survey on application security programs
In this whitepaper learn about the state of application security programs and practices of 488 surveyed respondents, and discover how mature and effective these programs are.