Millions of Facebook Users Have Been Hacked

Facebook announced on Friday a security breach that allowed hackers to control as many as 50 million Facebook accounts.

The security issue was found by Facebook’s engineering team on Tuesday, and was said to have allowed hackers to access information that could have let them take over around 50 million account.

CEO Mark Zuckerberg remarked, “This is a very serious security issue, and we’re taking it very seriously.”

According to Facebook, the attackers identified a weakness in Facebook’s code regarding its “View As” feature, where users can see what their profile looks like to other users on the platform.

Hackers were able get access tokens, which are digital keys which let people stay logged into the service without having to re-enter their passwords. These could be used to control other people’s accounts. The tokens have already been reset by the company and has also reset tokens for an additional 40 million accounts who used the “View As” feature in the last year as a precautionary measure, for a total of 90 million accounts. Facebook had 2.23 billion monthly active users as of June 30.

The “View As” feature has been suspended as the company reviews its security.

“Security is an arms race, and we’re continuing to improve our defenses,” Zuckerberg said. “This just underscores there are constant attacks from people who are trying to underscore accounts in our community.”

Zuckerberg’s full post on Facebook reads:

I want to update you on an important security issue we’ve identified. We patched the issue last night and are taking precautionary measures for those who might have been affected. We’re still investigating, but I want to share what we’ve already found:

On Tuesday, we discovered that an attacker exploited a technical vulnerability to steal access tokens that would
allow them to log into about 50 million people’s accounts on Facebook.

We do not yet know whether these accounts were misused but we are continuing to look into this and will update when we learn more.

We’ve already taken a number of steps to address this issue:

1. We patched the security vulnerability to prevent this attacker or any other from being able to steal additional access tokens. And we invalidated the access tokens for the accounts of the 50 million people who were affected – causing them to be logged out. These people will have to log back in to access their accounts again. We will also notify these people in a message on top of their News Feed about what happened when they log back in.

2. As a precautionary measure, even though we believe we’ve fixed the issue, we’re temporarily taking down the feature that had the security vulnerability until we can fully investigate it and make sure there are no other security issues with it. The feature is called “View As” and it’s a privacy tool to let you see how your own profile would look to other people.

3. As an additional precautionary measure, we’re also logging out everyone who used the View As feature since the vulnerability was introduced. This will require another 40 million people or more to log back into their accounts. We do not currently have any evidence that suggests these accounts have been compromised, but we’re taking this step as a precautionary measure.

We face constant attacks from people who want to take over accounts or steal information around the world. While

I’m glad we found this, fixed the vulnerability, and secured the accounts that may be at risk, the reality is we need to continue developing new tools to prevent this from happening in the first place. If you’ve forgotten your password or are having trouble logging in, you can access your account through the Help Center.
Disclaimer: We have no position in Facebook, Inc. (NASDAQ: FB) and have not been compensated for this article.