Unfortunately, these weren't just specialty apps with few users. The apps had nearly 150 million downloads, and dozens of them have over 1 million downloads -- the largest (Snow Heavy Excavator Simulator) had over 10 million. The oldest apps were available since March 2017.

We've asked Google for comment. SimBad may have been difficult to stop compared to some malware, since it was piggybacking on otherwise legitimate apps and was focused on serving ads as opposed to stealing data. Even so, this illustrates a familiar problem with the Play Store: Google's current scanning techniques can still miss rogue apps like this, and customers can't always tell that an app is suspicious just by looking at it.