Used smartphones often hold past users' data.

• Position: INFO SECURITY

Gartner Inc. predicts the global market for refurbished smartphones will grow to 120 million units by 2017, up from 56 million in 2014. Recycling is generally a good thing; however, in this case, it may be risky. Deleting data on smartphones is not always easy and often is not done properly.

Recent research conducted by Blancco Technology Group and Kroll Ontrack studied the prevalence of data "ghosting" on resold devices and found that more than one-third of secondhand smartphones contain information created by past users.

According to that survey, "In an examination of 122 pieces of second-hand equipment, 48% of the hard disk drives and solid state drives contained residual data, while thousands of leftover emails, call logs, texts/SMS/IMs, photos, and videos were retrieved from 35% of the mobile devices."

In addition, the research found that 57% of used mobile devices and 75% of used hard drives purchased from Amazon, eBay, and Gazelle had previous unsuccessful deletion attempts.

These figures are worrisome given the growing secondhand marketplace for used devices and even more so within the context of increasing bring-your-own-device (BYOD)-policy prevalence, Legaltech News said. For example, without secure management of BYOD-enabled devices, data contained on resold employee devices may escape from company-secured networks.

"One of the more glaring discoveries from our study is that most people attempt in some way or another to delete their data from electronic equipment," Paul Henry, IT security consultant for Blancco, said in an announcement. "But while those deletion methods are common and seem reliable, they aren't always effective at removing data permanently and...