Feeds

Hacker pierces hardware firewalls with web page

No interaction required

The Essential Guide to IT Transformation

On Tuesday, hacker Samy Kamkar demonstrated a way to identify a browser's geographical location by exploiting weaknesses in many WiFi routers. Now, he's back with a simple method to penetrate hardware firewalls using little more than some javascript embedded in a webpage.

By luring victims to a malicious link, the attacker can access virtually any service on their machine, even when it's behind certain routers that automatically block it to the outside world. The method has been tested on a Belkin N1 Vision Wireless router, and Kamkar says he suspects other devices are also vulnerable.

"What this means is I can penetrate their firewall/router and connect to the port that I specified, even though the firewall should never forward that port," Kamkar told El Reg. "This defeats that security by visiting a simple web page. No authentication, XSS, user input, etc. is required."

Kamkar's proof-of-concept page forces the visitor to submit a hidden form on port 6667, the standard port for internet relay chat. Using a hidden value, the form surreptitiously coerces the victim to establish a DCC, or direct client-to-client, connection. Vulnerable routers will then automatically forward DCC traffic to the victim's internal system, and using what's known as NAT traversal an attacker can access any port that's open on the local system.

For the hack to work, the visitor must have an application such as file transfer protocol or session initiation protocol running on his machine. The hack doesn't guarantee an attacker will be able to compromise that service, but it does give the attacker the ability to probe it in the hope of finding a weak password or a vulnerability that will expose data or system resources.

"Most people have this false sense of security that 'well, I'm behind my router, nobody can connect to my ports,'" said Kamkar, the hacker behind the notorious Samy Worm that in 2005 took MySpace out of commission by adding more than 1 million friends to the author's account. "If you're going to keep a service open to the world, you'll probably have more upkeep" to make sure it's secure.

The problem is a hard one to solve, since NAT, short for network address translation, is included in many routers to give users a seamless experience when accessing a host of internet-based services and applications. The use of a software-based firewall on the client will help, but Kamkar warned that even then some ports may be accessible.

While Kamkar's proof-of-concept requires users to press a submit button, he said it's trivial to use javascript so no interaction is required after the page is visited.

Kamkar said he based his attack on IRC because many versions of Linux used to run routers support the protocol by default. He's based similar attacks on file transfer protocol and had success with both the Belkin and Airport Extreme routers and believes other services such SIP may work on those routers as well as other devices.

Your reporter was unable to get the IRC attack to work on a Netopia 3347-02, so mileage obviously varies. We're interested in hearing from Reg readers about what other routers are vulnerable. To test whether the attack can pierce your firewall, visit this page and specify the port of a service that's already running on your system. ®

Build a business case: developing custom apps

More from The Register

next story
14 antivirus apps found to have security problems
Vendors just don't care, says researcher, after finding basic boo-boos in security software
'Things' on the Internet-of-things have 25 vulnerabilities apiece
Leaking sprinklers, overheated thermostats and picked locks all online
iWallet: No BONKING PLEASE, we're Apple
BLE-ding iPhones, not NFC bonkers, will drive trend - marketeers
Only '3% of web servers in top corps' fully fixed after Heartbleed snafu
Just slapping a patched OpenSSL on a machine ain't going to cut it, we're told
How long is too long to wait for a security fix?
Synology finally patches OpenSSL bugs in Trevor's NAS
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
Israel's Iron Dome missile tech stolen by Chinese hackers
Corporate raiders Comment Crew fingered for attacks
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
prev story

Whitepapers

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.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
Backing up Big Data
Solving backup challenges and “protect everything from everywhere,” as we move into the era of big data management and the adoption of BYOD.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Why and how to choose the right cloud vendor
The benefits of cloud-based storage in your processes. Eliminate onsite, disk-based backup and archiving in favor of cloud-based data protection.