Yahoo Says Hackers Stole Data on 500 Million Users in 2014 - The New York Times

Also see How to Protect Yourself After the Yahoo Attack (NYT) and How Many Times Has Your Personal Information Been Exposed to Hackers? (NYT)

"Yahoo announced on Thursday that the account information of at least 500 million users was stolen by hackers two years ago, in the biggest known intrusion of one company’s computer network.

In a statement, Yahoo said user information — including names, email addresses, telephone numbers, birth dates, encrypted passwords and, in some cases, security questions — was compromised in 2014 by what it believed was a “state-sponsored actor.”"

Yahoo Says Hackers Stole Data on 500 Million Users in 2014 - The New York Times