Facebook reveals 50 million accounts have been attacked

The vulnerability was the result of the interaction of three distinct bugs:

First: View As is a privacy feature that lets people see what their own profile looks like to someone else. View As should be a view-only interface. However, for one type of composer (the box that lets you post content to Facebook) — specifically the version that enables people to wish their friends happy birthday — View As incorrectly provided the opportunity to post a video.

Second: A new version of our video uploader (the interface that would be presented as a result of the first bug), introduced in July 2017, incorrectly generated an access token that had the permissions of the Facebook mobile app.

Third: When the video uploader appeared as part of View As, it generated the access token not for you as the viewer, but for the user that you were looking up.

In a statement, Facebook said, "To protect people’s accounts, we’ve fixed the vulnerability. We have also reset the access tokens of the almost 50 million accounts we know were affected and we’ve also taken the precautionary step of resetting access tokens for another 40 million accounts that have been subject to a View As look-up in the last year. Finally, we’ve temporarily turned off the View As feature while we conduct a thorough security review".

Facebook reveals 50 million accounts have been 'attacked' < Facebook News