Yahoo just announced yesterday about this hack that took place 2 years ago:
from New York Times
Quote from: http://www.nytimes.com/2016/09/23/technology/yahoo-hackers.html
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.”
from New York Times



