As a result of research carried out by experts at the University of Cambridge, it turned out that in the sold old mobile phones, even despite the "cleaning" of the memory, some information remains. Even resetting to "Factory settings" does not help.
The market for used smartphones is huge - in the USA alone it is 630 million units, and its growth trend will continue until at least 2018. The researchers tested 21 phones from Google, HTC, LG, Motorola and Samsung. In each case, they managed to recover SMS, Google account credentials, and messaging apps.
In addition, a key application remains on the devices, with which you can access the page on Facebook. Sometimes the memory cells of the phone, where photos and videos are stored, are not really cleared.
This is definitely to blame for the Android software developer - Google and phone manufacturers who create an imperfect platform, untimely upgrades and software updates. The conclusion made by the experts from Cambridge is one - no matter how hard you try to "clean" your mobile phone before the sale, there will still be something "interesting" there.
In this regard, it is worth listening to the cybersecurity experts of the Norwegian company Thorsheim, although the method they proposed is very radical, but reliable: take your old phone and smash it with a hammer.