Facebook Discovered Security Breach Affecting 50 Million Accounts, Stock Slides

Another day, another major security breach, and even more pain for Facebook which in recent months has failed to keep up with the FANG euphoria.

Facebook said that on September 25 it discovered a security breach which affected almost 50 million accounts. The company said it’s investigating the breach, which allowed hackers to take over a person’s account.

In the statement, Facebook said 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.”

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.

The social network added that it has “yet to determine whether these accounts were misused or any information accessed.” It also doesn’t know “who’s behind these attacks or where they’re based.”

As part of its response, the social-media network said that it has fixed the vulnerability, reset the access tokens of the almost 50 million accounts we know were affected to protect their security, turned off the “View As” feature, and told law enforcement authorities about the breach.

Shares declined over 2% percent on the news.

… with the drop enough to push the Nasdaq lower:

Full  Facebook statement below:

Security Update

By Guy Rosen, VP of Product Management

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.

Here is the action we have already taken. First, we’ve fixed the vulnerability and informed law enforcement.

Second, we have reset the access tokens of the almost 50 million accounts we know were affected to protect their security. We’re also taking 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. 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. After they have logged back in, people will get a notification at the top of their News Feed explaining what happened.

Third, we’re temporarily turning off the “View As” feature while we conduct a thorough security review.

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.

Since we’ve only just started our investigation, we have yet to determine whether these accounts were misused or any information accessed. We also don’t know who’s behind these attacks or where they’re based. We’re working hard to better understand these details — and we will update this post when we have more information, or if the facts change. In addition, if we find more affected accounts, we will immediately reset their access tokens.