Facebook Discovers Security Issue Affecting Almost 50 Million Accounts [u]

Facebook has just announced they uncovered a security issue earlier this week, which affects nearly 50 million accounts:

On the afternoon of Tuesday, September 25, our engineering team discovered a security issue affecting almost 50 million accounts. 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.

So what was stolen? Facebook access tokens, which essentially lets a hacker take over someone’s account. The news comes ahead of a Taiwan hacker’s claim where he would be live streaming the take over of Facebook founder Mark Zuckerberg’s account.

Facebook says they have fixed the security loophole and have contacted law enforcement.

Secondly, they have “reset the access tokens of the almost 50 million accounts we know were affected to protect their security,” while doing the same for an additional 40 million accounts that used the “View As” look up in the past year. This means 90 million people will have to login again to Facebook on all platforms. The social network says they will notify users if they have been affected.

The third move, says Facebook, is the “View As” feature has been temporarily disabled.

How did this security lapse come about? Facebook explains:

This attack exploited the complex interaction of multiple issues in our code. It stemmed from a change we made to our video uploading feature in July 2017, which impacted “View As.” The attackers not only needed to find this vulnerability and use it to get an access token, they then had to pivot from that account to others to steal more tokens.

Facebook says there is no need for people to change their passwords. If users are concerned about their accounts, they can visit the “Security and Login” section of the social network and hit a one-click log out option to sign out their account from all accounts.

Were you affected by this security breach at Facebook?