Google has removed a series of apps from the Play Store that were part of a massive ad fraud botnet. According to White Ops’ Satori mobile security team, the botnet, dubbed ‘Terracotta’, promised users free shoes, sneakers, and even tickets and coupons if they installed the applications on their devices. But instead, the apps downloaded and ran a modified version of WebView, a slimmed-down version of Google Chrome, loading ads and gaining revenue from fake ad impressions. The malicious apps can also wear out batteries and eat your mobile data.