Facebook passwords by the hundreds of millions sat exposed in plain text
The social network plans to notify all those users whose passwords were not encrypted on its internal servers.
Hundreds of millions of passwords were an open book on Facebook's internal servers.
An internal investigation at Facebook in January found that all those passwords were stored in plain text, meaning it was possible for the social network's employees to easily come across and potentially abuse the login credentials.
The company found "no evidence to date" that any staffers improperly accessed those passwords, Pedro Canahuati, Facebook's vice president of engineering, security and privacy, said in a blog post Thursday.
The internal investigation was first reported byKrebs on Security.
Facebook said it will be notifying hundreds of millions of Facebook Lite users, tens of millions of other Facebook users and tens of thousands of Instagram users. The company said it first discovered the problem as part of a routine security review in January.
Facebook has more than 2.3 billion monthly users, and Instagram has more than 1 billion.
Facebook said it hashes and encrypts passwords, but it's unclear how hundreds of millions of accounts had their passwords in plain text on internal company servers. It is still investigating the cause.
The social media giant isn't alone in this sort of security shortfall. Last May, Twitter advised 330 million users to change their passwords after discovering a bug that stored them in plain text on its internal logs. Github had a similar flubrevealed last May.