Data about half a billion Yahoo! users was snatched in 2014, it revealed.
It includes personal information included names and email addresses, as well as the details of security questions and answers which were unencrypted.
Yahoo! alleged that the data was “stolen by what we believe is a state-sponsored actor”.
The FBI is now investigating.
Yahoo!’s admission comes after reports last month claimed a hacker was trying to sell details for 200mln users.
The Nasdaq quoted internet giant has advised any user that hasn’t changed passwords since 2014 to do so.
It is clearly another piece of worrying news for internet users generally and Yahoo! users specifically, while for the growing legion of data and cyber security companies it further underlines the increasing profile and necessity of their businesses.
Story by ProactiveInvestors