Information from at least 500 million Yahoo accounts was stolen from the company in 2014, the company said Thursday, indicating it believes a state-sponsored actor was behind the hack.
The theft may have included names, email addresses, telephone numbers, dates of birth, and in some cases, encrypted or unencrypted security questions and answers
Approximately 1 billion people globally engage with Yahoo each month. About 250 million use Yahoo Mail, while another 81 million use Yahoo Finance and tens of millions use Yahoo Fantasy Sports. Yahoo said it was notifying potentially affected users and taking steps to secure their accounts, such as invalidating unencrypted security questions and answers. Users who haven’t changed their passwords since 2014 should do so, it said.