Stalkerware for mobile is easy to get by these days and you don't have to look further than Android's official store. While Google is quick to boot such apps when reported, some linger on adding thousands of installations.

Yesterday, researchers from Avast reported to Google four stalkerware apps believed to be the work of a Russian developer. They were promptly booted from the official Android store, but new ones have been discovered.

The functionality of these apps allowed someone to spy on people without leaving a trail on the device. This types of apps is often used to secretly monitor employee or life partners.

Nikolaos Chrysaidos from Avast found today three new stalkerware apps that have been installed tens of thousands of times; and they are yet to be removed.

"These apps are highly unethical and problematic for people’s privacy and shouldn’t be on the Google Play Store, as they promote criminal behavior, and can be abused by employers, stalkers or abusive partners to spy on their victims." - Nikolaos Chrysaidos

Stats from Google Play show that two of them - Spy Tracker and SMS Tracker, have over 50,000 installations. A third one named Employee Work Spy is less popular, with more than 10,000 installations. Avast says that all the apps have been installed over 130,000 times.

These are not top-of-the-line apps and need to be added manually to the target device. They ask for an email address where it delivers a password to access the spying software.

To make the spying app invisible to the victim, a second program needs to be installed, which instructs towards uninstalling the initial app.

"Finishing the setup there is nothing in app drawer - no icon - hidden," Avast told BleepingComputer.

Typically, their spying capabilities are limited to tracking the target's location, grabbing the contacts list, SMS and call history. On rooted devices they can also collect WhatsApp and Viber messages, Avast says in a blog post today.

To hide the true purpose of their apps, developers of stalkerware promote their products as parental control apps. However, reading the description of a different picture is painted, attracting users that want to spy on partners suspected of cheating, says Chrysaidos.

Update [7/17/19, 16:07 EST]: Google has pulled from Play store the remaining three stalker apps reported by Avast today, a representative told BleepingComputer.