"This is a classic case of "information asymmetry," said University of Washington law professor Ryan Calo, meaning when companies, government agencies or police departments have more information about your online habits than you even realize is out there.
"There's an enormous underestimation of your digital footprint," Calo said. "You might not realize how much your data is being stored, but you also might not realize how many parties have access to it. Think about all the uses to which this information can be put."
Webber, in this case, did just that.
"Not every company stores this information," he said, "but the ones that do is another chance for us to gather intelligence."
But Calo says the size of someone's online footprint depends on much more than their own activity."