Feeds

Attack reads smudges to retrieve Android password patterns

Oily residue 'surprisingly persistent'

Beginner's guide to SSL certificates

Smudges left on Android touch screens leave tell-tale signs that can often be used to recover password pattens used to lock the phones, according to research presented earlier this week.

The smudge attacks work by photographing Android handsets from a variety of angles using standard cameras and lights. The oily residues from fingers sliding across the touch-screen surface are then analyzed using standard computers running photo-editing software.

“We believe smudge attacks are a threat for three reasons,” the researchers wrote in a paper presented at the Fourth Usenix Workshop on Offensive Technologies, which took place on Monday in Washington DC.

“First, smudges are surprisingly persistent in time. Second, it is surprisingly difficult to incidentally obscure or delete smudges through wiping or pocketing the device. Third and finally, collecting and analyzing oily residue smudges can be done with readily-available equipment such as a camera and a computer.”

In one experiment that simulated an attack under ideal circumstances – in which touch screens weren't wiped – the researchers were able to recover the entire password pattern 68 per cent of the time if the phone first had been held to the user's face. Partial patterns were recovered 96 per cent of the time. Facial contact ensured there was enough skin oil to cause broad smudging, the researchers said.

A separate experiment, in which the touch screen was put in a user's pocket and allowed to move around slightly, was intended to simulate more realistic usage scenarios.

“Surprisingly, in all cases, the smudge was classified as perfectly retrievable,” the researchers wrote. “Simple clothing contact does not play a large role in removing smudges. However, on closer inspection, information was being lost. The directionality of the smudge often could no longer be determine [sic].”

Although the techniques could be applied to other types of smartphones, it was applied to two models of Android phones, which allow a user to trace a pattern on an on-screen 3x3 grid before the devices can be used. With 389,112 possible patterns, cracking the patterns would on average take many more attempts than the 20 unsuccessful tries permitted by the smartphone operating system. (After that, a user must enter credentials for a valid Google identity to access the phone.)

The experiments were carried out on two separate Android models, the HTC G1 and the HTC Nexus1. The researchers were Adam J. Aviv, Katherine Gibson, Evan Mossop, Matt Blaze and Jonathan M. Smith, and were all from the Computer and Information Science Department at the University of Pennsylvania. A PDF of their paper is here (warning: PDF). ®

Protecting users from Firesheep and other Sidejacking attacks with SSL

More from The Register

next story
Spies would need SUPER POWERS to tap undersea cables
Why mess with armoured 10kV cables when land-based, and legal, snoop tools are easier?
Early result from Scots indyref vote? NAW, Jimmy - it's a SCAM
Anyone claiming to know before tomorrow is telling porkies
Jihadi terrorists DIDN'T encrypt their comms 'cos of Snowden leaks
Intel bods' analysis concludes 'no significant change' after whistle was blown
Israeli spies rebel over mass-snooping on innocent Palestinians
'Disciplinary treatment will be sharp and clear' vow spy-chiefs
TOR users become FBI's No.1 hacking target after legal power grab
Be afeared, me hearties, these scoundrels be spying our signals
Hackers pop Brazil newspaper to root home routers
Step One: try default passwords. Step Two: Repeat Step One until success
China hacked US Army transport orgs TWENTY TIMES in ONE YEAR
FBI et al knew of nine hacks - but didn't tell TRANSCOM
Microsoft to patch ASP.NET mess even if you don't
We know what's good for you, because we made the mess says Redmond
NORKS ban Wi-Fi and satellite internet at embassies
Crackdown on tardy diplomatic sysadmins providing accidental unfiltered internet access
prev story

Whitepapers

Providing a secure and efficient Helpdesk
A single remote control platform for user support is be key to providing an efficient helpdesk. Retain full control over the way in which screen and keystroke data is transmitted.
WIN a very cool portable ZX Spectrum
Win a one-off portable Spectrum built by legendary hardware hacker Ben Heck
Saudi Petroleum chooses Tegile storage solution
A storage solution that addresses company growth and performance for business-critical applications of caseware archive and search along with other key operational systems.
Protecting users from Firesheep and other Sidejacking attacks with SSL
Discussing the vulnerabilities inherent in Wi-Fi networks, and how using TLS/SSL for your entire site will assure security.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.