Ever had low battery on your phone while out and about? Of course you have. Well, bizarrely that could have been used to track you. The disturbing way this could happen relates to how you access websites from your mobile phone.
The software that lets you load a website is able to see what the battery status is of your device, known as battery status API. This allows the possibility of positive things, such as loading a more basic site if someone has very low levels of power.
However, it could also be used to see what else you are browsing. The way this works is this. Say you access a website for your local vegetarian restaurant, and your phone has low battery levels. The site picks this up, and gives you a less complicated version as a result to conserve your battery.
BUT, let’s say at the same time you also look up a steakhouse, feeling a little weakwilled about your ethical diet choices.
Even if you used a different browser, in private mode and through a VPN, it could still be possible to connect your phone to both of those websites, if both of them had the same advert on the page.
The longer you stayed there, with battery depleting at the same level for both pages, the more clearly the two would be linked.
Steven Englehardt and Arvind Narayanan, from Princeton University, said they found two examples of scripts actually designed to track people through their battery life.
One of them ‘retrieves the current charge level of the host device and combines it with several other identifying features,’ they said.
They were able to ‘fingerprint’ devices by using charge level, charging status and IP address.
Companies could potentially use the information to manipulate you into buying things you wouldn’t normally, according to security expert Lukasz Olejnik.
‘When battery is running low, people might be prone to some – otherwise different – decisions,’ he said. ‘In such circumstances, users will agree to pay more for a service.’
