Facebook said it has discovered a security breach that affected nearly 50 million user accounts.
The issue which was found by its engineering team on Tuesday afternoon was made known to public on Friday.
“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,” the company said in a statement.
Facebook said that hackers exploited the “View As” feature on the service. The company said that it has taken steps to fix the security problem and alerted law enforcement.
“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.”
The Menlo Park, Calf.-based Facebook said it is taking three steps to ensure its users accounts are safe:
1. Fixing the vulnerability and informing law enforcement;
2. Resetting “the access tokens of the almost 50 million accounts we know were affected to protect their security”;
3. Temporarily turning off the “View As” feature “while we conduct a thorough security review.”
In addition, the Mark Zuckerberg-led company said it is taking the precautionary measure of resetting access tokens for another 40 million accounts that were “subject to a ‘View As’ look-up in the last year,” bringing the total to 90 million accounts who will now have to log back into the service.
Zuckerberg also alerted the breach on his Facebook page. Read more on his Facebook page.