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Facebook App Exposed Data of 120 Million Users

Facebook App Exposed Data of 120 Million Users

A recently addressed privacy bug on resulted in the data of over 120 million users who took personality quizzes on Facebook to be publicly exposed.

Patched as part of Facebook’s Data Abuse Bounty Program, the vulnerability resided in serving users’ data to any third-party that requested it, something that shouldn’t normally happen.

Facebook launched its Data Abuse Bounty Program in April, as part of its efforts to improve user privacy following the Cambridge Analytica scandal. The company also updated its terms on privacy and data sharing, but also admitted to tracking people over the Internet, even those who are not Facebook users.

The issue in was reported by Inti De Ceukelaire, who discovered that, when loading a personality test, the website would fetch all of his personal information from and display it on the page.

Websites shouldn’t normally be allowed to access the information, as web browsers do prevent such behavior. The data requested from, however, was wrapped in JavaScript, meaning that it could be shared with other websites.

“Since NameTests displayed their user’s personal data in JavaScript file, virtually any website could access it when they would request it,” the researcher explains.

To verify that this was indeed happening, he set up a website that connected to and would fetch information about the visitor. The access token provided by could also be used to gain access to the visitor’s posts, photos and friends, depending on the permissions granted.

“It would only take one visit to our website to gain access to someone’s personal information for up to two months,” De Ceukelaire says.

Another issue the researcher discovered was that the user information would continue to be exposed even after they deleted the application. With no log out functionality available, users would have had to manually delete the cookies on their devices to prevent their data from being leaked.

The bug was reported to Facebook’s Data Abuse program on April 22 and a fix was rolled out by June 25, when the researcher noticed that third-parties could no longer access visitors’ personal information as before.

The vulnerability could “have affected Facebook information people shared with To be on the safe side, we revoked the access tokens for everyone on Facebook who has signed up to use this app. So people will need to re-authorize the app in order to continue using it,” Facebook said.

The social platform also donated $8,000 (they apparently doubled the $4,000 bounty because the researcher chose to donate it to charity) to the Freedom of the Press foundation.

“I also got a response from NameTests. The public relations team claims that, according to the data and knowledge they have, they found no evidence of abuse by a third party. They also state that they have implemented additional tests to find such bugs and avoid them in the future,” the researcher notes.