Feeds

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

Shut the back door!

The Power of One eBook: Top reasons to choose HP BladeSystem

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. ®

Designing a Defense for Mobile Applications

More from The Register

next story
Secure microkernel that uses maths to be 'bug free' goes open source
Hacker-repelling, drone-protecting code will soon be yours to tweak as you see fit
How long is too long to wait for a security fix?
Synology finally patches OpenSSL bugs in Trevor's NAS
Roll out the welcome mat to hackers and crackers
Security chap pens guide to bug bounty programs that won't fail like Yahoo!'s
HIDDEN packet sniffer spy tech in MILLIONS of iPhones, iPads – expert
Don't panic though – Apple's backdoor is not wide open to all, guru tells us
Researcher sat on critical IE bugs for THREE YEARS
VUPEN waited for Pwn2Own cash while IE's sandbox leaked
Four fake Google haxbots hit YOUR WEBSITE every day
Goog the perfect ruse to slip into SEO orfice
Putin: Crack Tor for me and I'll make you a MILLIONAIRE
Russian Interior Ministry offers big pile o' roubles for busting pro-privacy browser
prev story

Whitepapers

Designing a Defense for Mobile Applications
Learn about the various considerations for defending mobile applications - from the application architecture itself to the myriad testing technologies.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Top 8 considerations to enable and simplify mobility
In this whitepaper learn how to successfully add mobile capabilities simply and cost effectively.
Seven Steps to Software Security
Seven practical steps you can begin to take today to secure your applications and prevent the damages a successful cyber-attack can cause.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.