238 Google Play apps with >440 million installs made phones nearly unusable

Carefully concealed adware installed in Google-approved apps with more than 440 million installations was so aggressive that it rendered mobile devices nearly unusable, researchers from mobile security provider Lookout said Tuesday.

Once installed, the apps initially behaved normally. Then, after a delay of anywhere between 24 hours and 14 days, the obfuscated BeiTaAd plugin would begin delivering what are known as out-of-app ads. These ads appeared on users' lock screens and triggered audio and video at seemingly random times or even when a phone was asleep.

There's no indication that CooTek will be banned or otherwise punished for breaching Play terms of service on such a mass scale and for taking the steps it did to hide the violation.