Facebook says 50 million accounts affected by security issue

Facebook has confirmed that there was a security issue that has compromised at least 50 million accounts.

In a statement on the social media company's Facebook Newsroom website, Guy Rosen, Facebook vice president of product management, said the company's engineering team found a security issue Tuesday afternoon.

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“We’re taking this incredibly seriously and wanted to let everyone know what’s happened and the immediate action we’ve taken to protect people’s security.

Our investigation is still in its early stages. But it's clear that attackers exploited a vulnerability in Facebook's code that impacted "View As", a feature that lets people see what their own profile looks like to someone else. This allowed them to steal Facebook access tokens which they could then use to take over people's accounts. 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."

Rosen said the vulnerability has been fixed and law enforcement has been contacted. The tokens have been reset for the known affected accounts.

“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,” Rosen said. “After they have logged back in, people will get a notification at the top of their News Feed explaining what happened.”

The “View As” feature is now temporarily turned off.

Rosen said the company does not know who did the attack or where it’s based.

If more affected accounts are found, access tokens will immediately be reset, he said.

“People’s privacy and security is incredibly important, and we’re sorry this happened. It’s why we’ve taken immediate action to secure these accounts and let users know what happened. There’s no need for anyone to change their passwords. But people who are having trouble logging back into Facebook — for example because they’ve forgotten their password — should visit our Help Center. And if anyone wants to take the precautionary action of logging out of Facebook, they should visit the “Security and Login” section in settings. It lists the places people are logged into Facebook with a one-click option to log out of them all.”

Rosen said the Facebook Newsroom post would be updated when there is more information on the attack or if facts change.