Feeds

Defend your phone against loose networks? There’s an app for that

Researchers unveil ‘middlebox detection’ software

Securing Web Applications Made Simple and Scalable

A group of researchers from the University of Michigan has released an Android app designed to defend against a common firewall vulnerability which they say commonly exposes smartphones on cellular networks.

The vulnerability, “off-path TCP sequence number inference”, can allow hijacking of Web pages users are trying to visit. The researchers say that some types of stateful firewalls, designed to drop packets without valid TCP sequence numbers, can be attacked by an insider that’s able to guess TCP sequence numbers of other users, and use this as the basis of a redirection.

The firewalls are common on cellular networks, the researchers say, with as many as 31.5 percent of the networks they tested using the stateful firewalls.

The researchers, Z. Morley Mao (a professor at Michigan) and doctoral student Zhiyun Qian, say that smartphones’ sandbox models can make them vulnerable to having a malware-infected machine inside the firewall read the incoming packet counters from an Android device, and let the attacker know when the sequence numbers advance. A successful attack also depends on having suitable malware on the Android phone, o as to get sequence numbers out of its sandbox.

"An attacker can try to guess at sequence numbers. It's usually hard to get feedback on whether a guessed number is correct, but the firewall middlebox makes this possible," Qian said. "The attacker can try a range of sequence numbers. The firewall will only allow one through if it is in the valid range."

A successful redirection allows the attacker to gain IDs and passwords of users on the same network. The researchers have also published a paper (PDF) describing other attack types. For example, the attacker could use TCP sequence number inference to create a spoofed IP address to perform denial-of-service on another server.

Their app, offered on Google Play, checks the firewall type on a network and alerts the user if it is vulnerable to the attack.

Mao and Qian are presenting their work at the IEEE Symposium on Security and Privacy in San Francisco. ®

Mobile application security vulnerability report

More from The Register

next story
LibreSSL RNG bug fix: What's all the forking fuss about, ask devs
Blow to bit-spitter 'tis but a flesh wound, claim team
Manic malware Mayhem spreads through Linux, FreeBSD web servers
And how Google could cripple infection rate in a second
NUDE SNAPS AGENCY: NSA bods love 'showing off your saucy selfies'
Swapping other people's sexts is a fringe benefit, says Snowden
Own a Cisco modem or wireless gateway? It might be owned by someone else, too
Remote code exec in HTTP server hands kit to bad guys
British data cops: We need greater powers and more money
You want data butt kicking, we need bigger boots - ICO
Crooks fling banking Trojan at Japanese smut site fans
Wait - they're doing online banking with an unpatched Windows PC?
NIST told to grow a pair and kick NSA to the curb
Lrn2crypto, oversight panel tells US govt's algorithm bods
prev story

Whitepapers

Reducing security risks from open source software
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
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.
Application security programs and practises
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Consolidation: the foundation for IT and business transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.