Facebook security breach affects millions

Hackers exploited the ‘View As’ feature UK accounts locked as loophole fixed

Social media giant Facebook has suffered a security breach affecting nearly 50 million users.

In a blog post, the company says hackers exploited its “View As” feature, which lets people see what their profiles look like to someone else.

Facebook says it has taken steps to fix the security problem and alerted law enforcement. In a post on the social network’s news site, Facebook vice-president of product management Guy Rosen said: “On the afternoon of Tuesday, 25 September 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’ ... 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.”

It was unclear whether any UK users had been hit, but some reported getting a message when they tried to log in that said: “Recent activity may have affected your account’s security, so we’ve locked it.

“We’ll walk you through a few steps to confirm your identity and help you access your account.”

Mr Rosen outlined the action Facebook had taken since the discovery, including fixing the issue and reporting it to law enforcement. He said: “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.”

Facebook has more than two billion users worldwide.

The social media platform has been hit by a series of problems this year, including the news that data analytics firm Cambridge Analytica had gained access to personal data from millions of user profiles.

Facebook chief executive Mark Zuckerberg said the company did not know yet whether hackers who had exploited the security vulnerability had misused any of the user account information.

Adam French, Which? consumer rights expert, said: “Facebook’s data breach will deeply concern users.

“It is critical that the company does all that it can to ensure affected people get clear information about what has happened and assists anyone negatively impacted.”