Facebook has filed a lawsuit against two Ukrainian nationals over a series of quizzes that was secretly stealing people's data.

The quiz apps had names like "Supertest," "Megatest" and "FQuiz," and came as browser extensions, which allowed the developers to harvest data and inject advertisements on your Facebook page, according to the lawsuit.

It affected 63,000 browsers, and had been happening between 2016 and 2018, targeting Russian users, Facebook said in its legal documents.

The lawsuit was filed late on Friday, and first reported by the Daily Beast. It names Gleb Sluchevsky and Andrey Gorbachov as the creators behind the malicious quizzes, who worked for a company called Web Sun Group.

Facebook did not respond to a request for comment. Sluchevsky and Gorbachov could not be reached for comment.

This lawsuit is not the first time that shady developers have used quizzes as a cover for malicious activity.

Facebook's Cambridge Analytica scandal siphoned data from 87 million Facebook users, by using quizzes on the social network to gather information from people's profiles. Quizzes include "sex compass" and personality tests.

Unlike Cambridge Analytica's tactics, the quizzes allegedly created by Sluchevsky and Gorbachov was done through browser extensions, requiring victims to download the malicious tools.    

Once installed, the quiz apps siphoned information like your name, gender, age and profile picture, as well as data on your friends. The apps also inserted advertisements on Facebook, pretending to come from the social network, the lawsuit alleged.

Sluchevsky and Gorbachov allegedly created these apps using fake profiles under names like "Amanda Pitt" and "Elena Stelmah." The quiz pages had tests like "Who are you of modern vampires" and "Check your brain: do you have it at all?"

The two had at least 13 fake accounts and pages on Facebook, the social network said.

In court documents, Facebook said it deleted all the fake accounts on Oct. 12, 2018. About a month later, hackers told the BBC that it had private messages from at least 81,000 Facebook accounts, which mostly belonged to users in Ukraine and Russia.

Facebook told the network that the account information had been stolen from "Malicious browser extensions" at the time.

The social network estimated that it lost $75,000 in damages from the malicious apps.

The lawsuit comes as Facebook looks to shift toward a focus on privacy, as CEO Mark Zuckerberg detailed in a blog post last Wednesday.

You can read the full lawsuit here: