They contain a ‘Trojan’ which displays adverts even if you’re not running the app you downloaded. It's part of the HiddenAds family, which Avast discovered by analysing the apps’ activity, features and information they were sending to and from the internet.

Out of the 47, seven had the ability to open the web browser on your phone and display yet more ads.

One of the other cheeky things these apps do is to hide their own icon so you can’t even see that it’s there. And even if you do manage to find it and delete it, the ads won’t necessarily go away.

Because they’re games, it’s likely the kids or younger phone users will download these apps without really noticing their low scores in Google Play, nor read the reviews which warn others about the incessant ads.

“Campaigns like HiddenAds may slip into the Play Store through obfuscating their true purpose or slowly introducing malicious features once already downloaded by users. It’s difficult to prevent adware campaigns since actors use one-off developer accounts for each app. While Google has been a great partner to remove malicious apps, users need to remain vigilant as they download new apps on their devices and check for telltale signs of a bad app such as negative reviews, extensive device permission requests and more,” said Jakub Vávra, threat analyst at Avast.

Often, developers avoid detection by Google’s automatic checking systems - which try to vet apps for malware and this type of adware – by creating a new developer account for each app. So this is one sign that an app might be malicious.

This kind of thing has been going on for years, so isn't new. Last year we reported on a similar discovery where 238 apps were found to contain adware.

The 47 apps have been downloaded over 15 million times, and the table below shows the 20  most popular, so don’t install these (and warn your family and friends about them):

App Name

Downloads

Draw Color by Number

1,000,000

Skate Board - New

1,000,000

Find Hidden Differences

1,000,000

Shoot Master

1,000,000

Stacking Guys

1,000,000

Disc Go!

1,000,000

Spot Hidden Differences 

500,000

Dancing Run - Color Ball Run 

500,000

Find 5 Differences

500,000

Joy Woodworker

500,000

Throw Master

500,000

Throw into Space

500,000

Divide it - Cut & Slice Game

500,000

Tony Shoot - NEW 

500,000

Assassin Legend

500,000

Flip King

500,000

Save Your Boy 

500,000

Assassin Hunter 2020

500,000

Stealing Run

500,000

Fly Skater 2020

500,000

How to avoid installing apps which will display ads

  • Read reviews as well as looking at the app’s rating in Google Play
  • Look at which permissions the app requests and deny any unnecessary ones
  • Install and use antivirus software for Android

The easiest way to prevent this happening is to carefully check the app you’re about to install. It’s tempting when your child is demanding that you install a free game immediately that you look over the description and hit the Install button.

Adware found in 47 games on Google Play

But taking time to check reviews (like those above) and read the on-screen prompts which ask permission to draw over other apps, access your contact list and other things will save you from pain later down the line.

Antivirus apps can also help to block installation of adware-infested apps, so it’s well worth a browse through our recommendations of the best antivirus for Android if the phone in question doesn’t have any security software on it.

Google is slowly getting better at preventing dodgy apps from appearing in the Play Store but it’s still a long way from eradicating them altogether.