In brief: Once again, Google has been forced to remove apps from its Play Store after they were found to contain adware. Both were selfie filter camera apps that had a combined 1.5 million+ downloads.

Researchers at Wandera, a mobile security company, discovered the two apps on Google's store. The first, Sun Pro Beauty Camera, had over one million downloads, while the second, Funny Sweet Beauty Selfie Camera, had over 500,000 downloads.

The apps were found to serve up intrusive out-of-app ads, which are not only a huge annoyance but may also brick devices, drain their batteries, and in some cases infect them with more malicious forms of malware.

"Adware enables authors to make money from affected devices and while it is typically regarded as more of a nuisance than a severe threat, these particular apps have more advanced functionality than your average adware," writes Wandera's Liarna La Porta.

The apps also request an unusual number of permissions, including being able to record audio at any time without user confirmation, allowing the app to activate after the phone has been booted, and allowing it to display content over another app.

Wandera notes that the apps' functionality is similar to the 85 adware-infested apps removed by Google last month, which displayed unskippable, difficult-to-close (full-screen) advertisements.

While we're always advised not to side-load apps from unofficial sources, it's best to check user reviews of apps from official stores to make sure they're legit. We recently heard of malware being found in CamScanner, a PDF maker with over 100 million downloads, while the Joker malware was discovered in 24 Play Store apps.