Whether we want to admit it or not, smartphones are fast becoming a technology we depend upon on an everyday basis. Whether it’s being able to communicate with friends and family throughout the day or capturing a spur of the moment memory, we carry our phones everywhere to keep us constantly connected and plugged in.
The problem with this, however, is that being in this constant state of connectivity can lead to some poor decision making. This includes browsing the darker side of the web during times of boredom or taking an inappropriate “selfie” and sending it off to someone in an attempt to flirt.
These decisions might not seem like a big deal in the moment but after some time, they might seem regrettable, especially when the user wants to re-sell their device or otherwise hand it off to someone else when upgrading to a newer model. The standard practice has always been to “wipe” one’s phone by performing a factory reset. This leaves the original owner of the device with the sense that all inappropriate web browsing, photos, and conversations have been deleted from the phone forever.
Following a recent study by software company Avast, though, users should be aware that this is definitely NOT the case.
The folks at Avast purchased 20 different Android phones on eBay and performed a series of data recovery operations using a plethora of publicly available forensic security tools to see what they could find. Out of the 20 devices, the group was able to recover 40,000 photos, including 1,500 family photos with children, 750 inappropriate images of men and women in various stages of undress (including 250 selfies of “what appears to be the previous owner’s manhood”), 750 e-mails and text messages, and 250 contacts with names and addresses.
Other items included a loan application, a completed sexual harassment course, Google search inquiries, and plenty of downloaded adult material.
News of this report is, in a word, sobering. When a device is wiped, all of the data stored to it never actually gets erased. Instead, the software managing the device’s content erases the index information for the file, thereby making the bits ready to be overwritten with new data. If a user performs a factory reset and then sells the device, the data never gets overwritten and so still exists; and with the right tools, it can still be tracked down and accessed.
Backtracking a bit, but worth noting about the report is the fact that it was 20 ANDROID phones that were used in this study. That’s because data recovery from an iPhone is more challenging due to the higher levels of protection Apple puts in the security stack; it also offers a much better secure-wipe routine, especially when comparing it to what Android has to offer, as well as what third-party apps promise to offer in the Google Play store. You see, when a user wipes an Apple device, the actual encryption keys are overwritten, which makes data recovery significantly more challenging. Android, for comparative purposes, does not necessarily offer hardware encryption, and so secure-wipe solutions aren’t consistent across the board.
Now, before you take your Android device and travel to the nearest lake to ensure its contents are never revealed, there are options for permanently deleting the content off one’s phones prior to re-selling it / giving it to someone else. Special disk-management and security tools, which include – to no surprise of anyone reading the report — Avast’s, are able to forever delete existing delete. The process takes longer than a typical factory reset, though, and is obviously more costly.
There is another option, and this involves focusing on the phone’s NAND flash memory. For those unfamiliar with the technology, the NAND flash memory is a common form of storage in mobile devices; the problem with it, though, is that it typically keeps redundant copies of old, stale data in areas of the phone that aren’t necessarily part of the device’s file system. If you own a phone and want to wipe it clean of all data, do a factory reset and then fill the phone’s storage with benign data — take a video of paint drying, snap 50 photos of your front lawn grass growing, etc. Once you see the storage space on your phone begin to fill up, you’ll know the previous data has been overwritten, and when you reach a point where the storage space if full, go ahead and do another factory reset.
This will confirm an added layer of overwrite and reset of the NAND flash on the device — it’s not a definite guarantee, though, that with the right tools and level of dedication, an individual won’t ever be able to access the data down the road. But it does make it that much harder.
Worth noting in this whole story is Google’s response to the report. The company pointed out that Avast used outdated devices and that its research did not “reflect the security protections in Android versions that are used by the vast majority of users.”
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