Developers employed a variety of tricks to populate Google Play with more than a dozen apps that bombard users with ads, even when the apps weren't being used, researchers said on Tuesday.
Among the tactics used to lower the chances of being caught by Google or peeved users: the apps wait 48 hours before hiding their presence on devices, hold off displaying ads for four hours, display the ads at random intervals, and split their code into multiple files, researchers with antivirus provider Bitdefender reported. The apps also contain working code that does the things promised in the Google Play descriptions, giving them the appearance of legitimacy. In all, Bitdefender found 17 such apps with a combined 550,000 installations.
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