What are the implications of these findings? As more people use smartphones, digital forensic investigators -- including police departments and law enforcement agencies -- are increasingly looking at such devices to recover usable evidence. Last year, for example, police in London announced that they were testing mobile phone data extraction devices to allow specialist teams to access, study and save any data stored on a suspect's mobile device. In the future, however, they may need to study not one device, but many, given the extent to which many people now own multiple devices.
On that front, the Glasgow researchers said they're now continuing their study to cross-reference forensic examinations of multiple devices used by the same person. "The very nature of the cloud environment encourages users to access data through multiple devices," they said, noting that they already have an experiment underway "to access residual artifacts from Gmail, Mozy, Ubuntu One and Evernote on end devices connected to these services." Their question is whether conducting a forensic analysis of multiple devices used by the same user will yield a greater number of recoverable files and artifacts.
"The first step was to say, is this an idea that's going to work, then we can say, in future research, how do we use this data to say something useful for a forensic investigator, in terms of merging evidence from different proxies into a single data set?" said paper co-author Tim Storer, speaking by phone. For example, if part of an Excel spreadsheet is found on one device, but not another two devices used by the same user, should it count as evidence? "There's often a tendency by forensic investigators to conflate data and evidence," he said, when a higher threshold is called for.
Going forward, the researchers said in their paper that they hope to detail "the data leakage risk that cloud applications introduce to corporate environments" in greater detail, as well as to "propose a set of security measures for both cloud providers and smartphone users to mitigate the potential risk of data leakage."
"These services are being used in corporate environments more and more ... so it's a potential source of risk for an organization," said Storer. "Sensitive documents may end up on someone's device that's subject to analysis." But businesses might minimize those types of risks by steering their employees to use devices from which it's more difficult to recover usable information, forensically speaking. Likewise, cloud service providers could offer their corporate customers specialized services that scrubbed all data stored by their mobile apps, once a user no longer needed to view it.