When Selling Your Used Smartphone, You Could Be Selling Your Personal Data

Security vendor Avast has warned smartphone owners to be extra careful when they are selling their devices, after recovering a hoard of personal data form used handsets which were subjected to a ‘factory reset.’

To prove that traces of deleted data could still pose a security risk, the company staged an experiment in the US. It purchased 20 smartphones online, and managed to extract hundreds of old photos, texts, emails, contact book entries and even a complete loan application.

Avast said it was entirely possible to establish the identity of up to four previous device owners using simple, off-the-shelf data recovery solutions.

“Images, emails, and other documents deleted from phones can be exploited for identity theft, blackmail, or for even stalking purposes. Selling your used phone is a good way to make a little extra money, but it’s potentially a bad way to protect your privacy,” warned Jude McColgan, president of Mobile at AVAST.

A hard bargain

After buying 20 second-hand smartphones from various online vendors, researchers at Avast got their hands on more than 750 emails and text messages, more than 250 contact details and at least 1,000 Google search queries.

Surprisingly, they also recovered thousands of personal photos including 1,500 photos of children and 750 photos of women “in various stages of undress”.

“The amount of personal data we retrieved from the phones was astounding. We found everything from a filled-out loan form to more than 250 selfies of what appear to be the previous owner’s manhood,” said McColgan.

“We purchased a variety of Android devices from sellers across the US and used readily available recovery software to dig up personal information that was previously on the phones. The take-away is that even deleted data on your used phone can be recovered unless you completely overwrite it.”

To make sure the data never comes back to haunt them, smartphone owners are advised to use specialised software for a ‘secure wipe’ before they put the devices on sale, like the free Anti-Theft app for Android offered by Avast itself.

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