Exactly who is it who hacked into Yahoo in 2013 and 2016?

well I suppose they will say it was the Russian governement, but my money is on an errant employee simply copied data then posted it somewhere to some hacker forum.

Data gets backed up, copied and moved around - making it so that no person can ever make their own copy of it and put it on a portable drive is very difficult.

All 1.5 billion Yahoo customers.

just assume you are hacked in both