3 min read

Facebook revealed last Friday that a major security breach compromised 50 million user accounts on Facebook.

The security attack not only affected user’s Facebook accounts but also impacted other accounts that were linked to Facebook. The hackers had exploited Facebook’s “View As” feature that lets people see what their own profile looks like to someone else. The hackers had stolen Facebook access tokens to hack into other user’s accounts. These tokens provide hackers with full control over victim’s account, including logging into third-party applications that use Facebook Login.

“We wanted to provide an update on the security attack that we announced last week. We fixed the vulnerability and we reset the access tokens for a total of 90 million accounts — 50 million that had access tokens stolen and 40 million that were subject to a “View As” look-up in the last year” wrote Guy Rosen, VP of product management.

Resetting the tokens required users to login into their Facebook accounts again as well as re-login into any accounts or apps that use Facebook.

As far as questions about the effects of this attack on the apps that used Facebook are concerned, Facebook is yet to find any impact. “We have now analyzed our logs for all third-party apps installed or logged in during the attack we discovered last week. That investigation has so far found no evidence that the attackers accessed any apps using Facebook Login”, states the Facebook post.

All the developers leveraging the official Facebook SDKs along with people checking the validity of their users’ access tokens were automatically protected, on resetting the access tokens.

However, to be extra careful, Facebook is developing a tool which will allow developers to manually identify users of the apps affected by the security breach so that they can be logged out. This will also prove to be beneficial for all those developers who don’t leverage Facebook’s SDKs or who don’t regularly check whether Facebook access tokens are valid.

Additionally, Facebook recommends that developers always use Facebook Login security best practices as a guideline. It recommends that a developer use Facebook’s official SDKs for Android, iOS, and JavaScript, as these automatically check the validity of access tokens. These also force a fresh login every time the tokens are reset by Facebook, thereby protecting users accounts. Another thing to keep in mind is that Facebook wants developers to use the Graph API. This keeps the information updated regularly and makes sure that users are logged out of apps in case they show any Facebook session as invalid.

“Security is incredibly important to Facebook. We’re sorry that this attack happened — and we’ll continue to update people as we find out more” reads the post.

For more information, check out the official announcement.

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