Another week, another sketchy Android app has been removed from the Google Play Store.

This time it was a group of about 60 apps that offered free footwear, coupons, or concert tickets if you left the app installed. However, these apps actually downloaded a secret web browser, which they used to commit ad fraud.

The apps had simple names like "get free sneakers," "free teeth whitening," "best game tips," and "store coupons."

According to White Ops, the security firm that discovered the scam, in just one week in June, these apps displayed over 2 billion fake ads on 65,000 infected Android phones.

Since late 2019, the fake ad campaigns have enlisted infected phones in a botnet White Ops calls Terracotta, as reported by ZDNet.

So far, no real harm has been done to the phones or their owners other than excessive battery drain and bandwidth consumption. However, the fact that the app can install other apps without the user being aware of it means that the Terracotta botnet could go rogue at a moment's notice.

Taking advantage of the White Ops discovery, Google removed these apps from Google Play and disabled them on users' phones.

To make sure your Android phone is not infected with such scams, download and install one of the best Android antivirus apps, harmless or not.