Feeds

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

Researchers unveil ‘middlebox detection’ software

Security for virtualized datacentres

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. ®

Secure remote control for conventional and virtual desktops

More from The Register

next story
Russian hackers exploit 'Sandworm' bug 'to spy on NATO, EU PCs'
Fix imminent from Microsoft for Vista, Server 2008, other stuff
Microsoft pulls another dodgy patch
Redmond makes a hash of hashing add-on
FYI: OS X Yosemite's Spotlight tells Apple EVERYTHING you're looking for
It's on by default – didn't you read the small print?
'LulzSec leader Aush0k' found to be naughty boy not worthy of jail
15 months home detention leaves egg on feds' faces as they grab for more power
Forget passwords, let's use SELFIES, says Obama's cyber tsar
Michael Daniel wants to kill passwords dead
FBI boss: We don't want a backdoor, we want the front door to phones
Claims it's what the Founding Fathers would have wanted – catching killers and pedos
Kill off SSL 3.0 NOW: HTTPS savaged by vicious POODLE
Pull it out ASAP, it is SWISS CHEESE
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Why cloud backup?
Combining the latest advancements in disk-based backup with secure, integrated, cloud technologies offer organizations fast and assured recovery of their critical enterprise data.
Win a year’s supply of chocolate
There is no techie angle to this competition so we're not going to pretend there is, but everyone loves chocolate so who cares.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Intelligent flash storage arrays
Tegile Intelligent Storage Arrays with IntelliFlash helps IT boost storage utilization and effciency while delivering unmatched storage savings and performance.