The malware, according to the firm Avast, is included on apps that are targeted toward English speaking as well as other language regions.
These malicious apps act as normal software for a period of time, sometimes as long as 30 days, before they begin serving up advertising claiming that there is a problem with the user’s device. The warnings pop up every time the user unlocks the device.
“This, of course, is a complete lie,” wrote Avast’s Filip Chytry in a blog post.
The ads warn users they should take action to protect themselves.
“However,” Chytry added, “if you approve you get re-directed to harmful threats on fake pages, like dubious app stores and apps that attempt to send premium SMS behind your back or to apps that simply collect too much of your data for comfort while offering you no additional value.”
Avast found that the most popular app containing the malware, or adware, as it is sometimes called, was the Durak card game app. According to the Play store, the app has been installed some 5 million to 10 million times.
Surprisingly, Avast found that some of the advertising leads to legitimate security apps on Google Play – although downloading the advertised software won’t actually end the warnings that appear when the phone is unlocked.
Chytry also questioned the strategy of selling security software through adware.
The online privacy experts at Avast suggest reading app descriptions and avoiding those with poorly written portrayals.
The description for Durak, for example, claims that it is “one of the most common and well known game.”