Android Security

Factory Reset Doesn’t Reset Much at All

August 15, 2014 - Written By Phil Bourget

We always hear about happenings with regards to the Global Android community specifically relating to the United States, as both Google and Android Headlines have headquarters there.  But today, we bring you something from ‘across the pond’, though it’s markedly larger than a pond, in the United Kingdom.  Tesco is a brand and chain of stores in the U.K., and they function much like a Wal-Mart does, having most things the average store-goer needs or could be distracted into wanting.

This includes the Tesco Hudl (pronounced like huddle, because you huddle around a tablet maybe?) Android tablet, only putting customers back 99 GBP for the Android 4.2-clad device.  No, this isn’t an advert, but there’s what you needed to know about the primary device involved today.  Since the price is low, and teenagers love both technology and creating data (whether it be ringtones or selfies or something else entirely), so this tablet is great for that.  But something that the tablet has been found to also be great for has just been revealed: restorability of ‘erased’ user data.  The processing package inside the Hudl, a Rockchip chipset, is said to be able to be manipulated, with the right tools and knowledge, and enough time, to allow a second-hand owner to see, access, interact with, and restore/use previous owners’ data.

Now, to define the ‘data’ that can be restored and misappropriated.  Data here means the files downloaded by the user, their photos that were taken with the device, music and movies loaded onto it, as well as Google and internet searches, Wi-Fi passwords and networks, and login information for various websites and apps.  Wait, I hit ‘factory reset, wipe all data’, why didn’t it do that?  Well, the ‘factory reset’ we think will get us back to being dandy and fresh out of the box as when we got it.  And it’s not just this Tesco tablet, it’s most if not all Android devices that have more than one step to securely and permanently delete your data.

This bit is a little technical, since it involves references to recovery mode and partitions, both of which aren’t regularly accessed by many or most smartphone and tablet owners.  Recovery mode, depending on the designer and version, can do the factory reset, but that only does so much.  It wipes clean the /data and /cache partition, where data about your downloaded apps is and goes, but it doesn’t wipe the /system partition, where system applications (the ones you can’t uninstall or remove) are and function from.  The most used applications by many are those, the system apps, and most people don’t want to delete part of their system, or don’t know how to.

The only truly secure way to remove yourself from a device is to make the data unreadable.  Factory resetting a device removes the registry telling file explorers and apps where to look for data, but not the data itself.  To get rid of your existence on that device, you need to make the data unreadable and unusable to others, by overwriting it with zeros, or empty bits, so it functions as empty, readily usable storage space for the new owner’s apps and data.

So next time you consider selling your smartphone to a friend or someone on EBay, Craigslist or the like, browse online from your computer or other device(s) to find a tutorial or two telling you what to delete, how to do it, and how to check if it was successful.  If you’ve ever sold a device, Android or iOS, how did you prepare it for sale, what did you wipe, or did you just leave what little was on there alone?  Let us know, and be careful when letting devices go to make sure your information and security don’t go with it.