“As Yahoo attempts to piece together how a hacker accessed 500 million user accounts back in 2014, the company has now admitted that some employees knew of a security breach when it happened. In a filing with the SEC, Yahoo said that while it only disclosed news of the attack in August, a ‘state-sponsored actor’ had accessed its network two years ago but it didn’t quite know the extent of the damage at the time.”

Source: Yahoo admits some staff knew of 2014 hack