Mobile batteries become prime target for hackers

Batteries have become a new security risk for smartphone users, with a group of security researchers saying they are able to transmit personal data to hackers.

Lukasz Olejnik, Gunes Acar, Claude Castelluccia and Claudia Diaz have written a paper outlining the risks, saying a piece of software used in the HTML5 web language transmits data such as how much power is still left in a battery so websites using the code can save power while browsing.

However, it can also be used maliciously to track people as they navigate around the web, revealing which sites they visit and what kind of data they are inputting.

Unlike other actions carried out on a mobile, such as downloading an application, you don't have to grant HTML5 permission to pass this information onto the wider world. Therefore, a smartphone will respond to battery information requests without checking with you whether that's OK.

As a user navigates around different mobile websites, this information will be transmitted from each site using HTML, meaning intelligent hackers could learn quite a lot about the owner.

And, unlike the security measures put in place by private browsers and VPNs, this HTML5 bug will let the internet know where you've been thanks to the hole that hasn't been patched.

The researchers argued in their paper that smartphone users should be able to grant or deny permission for this data to be broadcast, leaving it down to them whether their battery power is preserved when accessing certain websites or not. They should also be given more information about the type of data transmitted by their phone's battery, the researchers said.