Facebook has filed lawsuits against two app developers accused of generating fraudulent revenue using the social media giant’s advertising platform.

The company announced the legal action in a blog post-Tuesday.

“The developers made apps available on the Google Play store to infect their users’ phones with malware,” said Jessica Romero, director of platform enforcement and litigation. “The malware created fake user clicks on Facebook ads that appeared on the users’ phones, giving the impression that the users had clicked on the ads.”

The scheme uses a technique known as click injection, which relies on apps fraudulently generating ad clicks without the user’s knowledge to artificially inflate the amount of ad revenue. It’s a problem previously noted by security researchers. Often, developers create junk or easy-to-make apps which get downloaded millions of times, while in the background they’re clicking on invisible ads without the user’s knowledge.

Facebook said, in this case, two developers, LionMobi — based in Hong Kong, and JediMobi — based in Singapore — generated “unearned payouts” from the social media giant’s advertisement system.

By our count, the app developers have seen more than 207 million installs to date. Google spokesperson Scott Westover told TechCrunch that it had banned the app developers.

The social media giant said it refunded impacted advertisers.

A Facebook spokesperson did not immediately respond to a request for comment.

Updated on Wednesday with comment from Google.