Facebook says 50 million users affected by security breach

Facebook announced Friday that it recently discovered a security breach affecting nearly 50 million user accounts.

The company said hackers exploited the "View As" feature on the service.

"This allowed them to steal Facebook access tokens which they could then use to take over people's accounts," Facebook VP Guy Rosen wrote in a blog post. "Access tokens are the equivalent of digital keys that keep people logged in to Facebook so they don't need to re-enter their password every time they use the app."

Facebook alerted law enforcement, disabled the "View As" feature, is working fixing the security problem, and reset the access tokens of 50 million accounts that were affected and another 40 million as a precaution, Rosen wrote.

"As a result, around 90 million people will now have to log back in to Facebook, or any of their apps that use Facebook Login," he said. "After they have logged back in, people will get a notification at the top of their News Feed explaining what happened."

Rosen wrote that Facebook is "sorry this happened."

"Since we've only just started our investigation, we have yet to determine whether these accounts were misused or any information accessed," he wrote. "We also don't know who's behind these attacks or where they're based."

With the AP