Security researchers revealed this week that dozens of apps in the Google Play Store had secretly gathered data on tens of millions of users and sent it to a company linked to a U.S. defense contractor. Developers of Muslim prayer apps, QR code scanners and international weather apps were paid by a company called Measurement Systems to insert code that gave Measurement access to user data, without the developers fully knowing. Google says it has since banned these apps. Marketplace’s Meghan McCarty Carino speaks with Byron Tau, who covered this for The Wall Street Journal.