Janne Kytömäki, a Finnish software developer, was cruising Google’s (GOOG) Android Market for smartphone apps last year when he noticed something strange. Dozens of best-selling applications suddenly listed the same wrong publisher. It was as if Stephen King’s name had vanished from the covers of his books, replaced by an unknown author. Kytömäki realized the culprit was a piece of malware that was spreading quickly, and he posted his findings online.
Google responded swiftly. It flipped a little-known kill switch, reaching into more than 250,000 infected Android smartphones and forcibly removing the malicious code. “It was sort of unreal, watching something like that unfold,” says Kytömäki, who makes dice simulator apps. Kill switches are a standard part of most smartphones, tablets, and e-readers. Google, Apple (AAPL), and Amazon (AMZN) all have the ability to reach into devices to delete illicit content or edit code without users’ permission. It’s a powerful way to stop threats that spread quickly, but it’s also a privacy and security land mine.