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According to security experts, the popular Pattern Lock system, used to secure millions of Android phones, can be cracked within just five attempts while more complicated patterns are the easiest to crack.
Pattern Lock is a security measure that protects devices, such as mobile phones or tablets. In order to access a device’s functions and content, users must first draw a pattern on a grid of dots. If this matches the pattern set by the owner then the device can be used. However, users only have five attempts to get the pattern right before the device becomes locked.
A new research from Lancaster University, Northwest University in China, and the University of Bath, published on alphagalileo.org, shows for the first time that attackers can crack Pattern Lock reliably within five attempts by using video and computer vision algorithm software. The research was funded by the Engineering and Physical Sciences Research Council (EPSRC).
By covertly videoing the owner drawing their Pattern Lock shape to unlock their device, while enjoying a coffee in a busy café for example, the attacker, who is pretending to play with their phone, can then use software to quickly track the owner’s fingertip movements relative to the position of the device. Within seconds the algorithm produces a small number of candidate patterns to access the Android phone or tablet.
The attack works even without the video footage being able to see any of the on-screen content, and regardless of the size of the screen. Results are accurate on video recorded on a mobile phone from up to 2.5 metres away.
Complex patterns, which use more lines between dots, are used by many to make it harder for observers to replicate. However, researchers found that these complex shapes were easier to crack because they help the fingertip algorithm to narrow down the possible options.
During tests, researchers were able to crack all but one of the patterns categorised as complex within the first attempt. They were able to successfully crack 87.5 per cent of median complex patterns and 60 per cent of simple patterns with the first attempt.
In addition, given people often use the same pattern across multiple devices a pattern obtained from one device could be used to access a second device.
Dr Zheng Wang, principle investigator and co-author of the paper, said: “Pattern Lock is a very popular protection method for Android Devices. As well as for locking their devices, people tend to use complex patterns for important financial transactions such as online banking and shopping because they believe it is a secure system. However, our findings suggest that using Pattern Lock to protect sensitive information could actually be very risky.”
“Despite the popular belief that more complex patterns give better protection, this attack actually makes more complex patterns easier to crack and so they may be more secure using shorter, simpler patterns,” Guixin Ye, the leading student author from Northwest University, added.