Out-of-context ads, or out-of-app ads, is a relatively new technical term that refers to mobile ads that are shown inside a popup or on the entire screen, separate from the original app.
These types of ads have been banned on the Play Store since February 2020, when Google ruled that these ads make it impossible for users to determine the app from where the ad originated, opening a loophole on Android devices for silent ad spam.
However, while the original ban on out-of-context ads brought bans for 600 Android apps, this didn't mean that app developers stopped abusing this mechanism.
Both in June and October 2020, Google was forced to intervene again and ban a wave of 38 and 240 apps, respectively, that continued to abuse this mechanism.
Both app clusters were discovered by White Ops; a security firm specialized in detecting bot and advertising fraud.
But this week, White Ops said that it recently discovered another app cluster that also abused out-of-context ads, a cluster that managed to stay undetected more than the others, for more than two years.
Most of these 164 apps mimicked more popular applications, copying both functionality and names from more established apps in order to garner quick downloads.
In total, White Ops said the apps achieved their goal and were downloaded more than 10 million times before they were discovered and reported to Google's security team.
The names of all the 164 Android apps are too long to include in this news article, but users can find a complete list in White Ops' report.
According to Google Play Store rules, the apps were removed from the store and disabled on users' devices, but users still need to manually remove them from their phones.