If you’ve ever discovered full-screen ads popping up on your Android phone, you’re not alone. This isn’t a new way Google has decided to show ads: they’re caused by malicious apps which often masquerade as legitimate games or even – ironically – adblockers.
Avast recently discovered 47 such games which had this despicable behaviour and reported them to Google. Around 17 remain available to download, including Disc Go!, on the Google Play Store.
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.
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.
Author: Jim Martin, Executive Editor, Tech Advisor
Jim has been testing and reviewing products for over 20 years. His main beats include VPN services and antivirus. He also covers smart home tech, mesh Wi-Fi and electric bikes.
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