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Dirty smartphones: Devices keep traces of files sent to the cloud

Research shows Android devices, iPhones could be at risk; though cloud service encryption updates could help

By , Network World
March 26, 2013 04:57 PM ET
dirty smartphone
Credit: Stephen Sauer

Network World - When smartphone users upload files to cloud-based services, remnants of those files often remain on their handheld device, even if the data is meant to be stored only in the cloud, researchers have found.

The consequence is that hackers could potentially access files stored in the cloud, or get access to cloud accounts, using leftover data stored on your Android device, iPhone or other smartphone.

"That smartphones can essentially remember deleted information poses a huge risk to organizations that issue smartphones to employees and to organizations that don't explicitly disable the use of personal devices for work-related computing," says Pravin Kothari, founder and CEO of CipherCloud, a maker of cloud encryption software.

The tracing of leftover data on smartphones is not for the layperson, Kothari says, but could be looked at as the modern-day equivalent of Dumpster-diving for personal information.

[ MORE SECURITY: 9 classic hacking, phishing and social engineering lies ]

Researchers at the University of Glasgow ran a variety of tests to come to their conclusions (read the PDF of the report here). Phones tested included the HTC Desire, running Android 2.1, and an iPhone 3S running iOS 3, and cloud-based file storage systems tested included Box, Dropbox and SugarSync.

A hard reset of the phones being tested was done before 20 files were created on each of the devices, including images, documents, PDFs and music files. Researchers then "manipulated" the phones, by either powering them off, caching the applications or both. As a control, some of the phones were left in active state without any caching. Researchers then did a "data dump" of the phones by copying the memory onto a flash drive, which they then analyzed.

Researchers found a variety of metadata leftover after the files had been uploaded to the cloud services. Email addresses of users and transaction logs of which files were uploaded to the cloud were visible, for example. Researchers said they were even able to piece together various metadata to get a URL address of where a file was located in Box's cloud. Researchers also found that all files marked for "offline access" were able to be recovered from both the Android and iOS devices. Even some deleted files were still traceable on the SD card of the Android device.

Files were recovered from both the Android smartphone and its SD card, while the recovered data from the iOS device was recovered from the phone's internal memory (the iPhone 3S does not use an SD card).

In most circumstances, the researchers found that if the applications had been cached, then recovering the files was more difficult, except for when using Box on the iOS device, in which case the same number of files was able to be recovered even after caching.

"Smartphone devices which access cloud storage services can potentially contain a proxy view of the data stored in a cloud storage service," the research concludes. Accessing the proxy data can lead to further data being exposed, they add. Files that were not viewed on the smartphone, but were in the user's cloud storage account, could not be recovered, although in some cases a thumbnail of a JPEG that had not been viewed on the phone was able to be seen.

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