Shortly before it was acquired by Verizon, the company had said one billion users were hit by what was considered the largest known breach of a company.
It was the biggest breach of a company of all time. And now, it is even bigger.
Verizon Communications, which now owns Yahoo, said Tuesday that a previously disclosed hack of the internet service’s computer network in 2013 affected all of its three billion user accounts.
Last year, Yahoo said the attack on its network had affected one billion users. It also disclosed a separate attack, which occurred in 2014, that had affected 500 million accounts.
Digital thieves made off with names, birth dates, phone numbers and passwords of users that were encrypted with security that was easy to crack.
The intruders also obtained the security questions and backup email addresses used to reset lost passwords — valuable information for someone trying to break into other accounts owned by the same user, and particularly useful to a hacker seeking to break into government computers around the world.
After years of struggling, Yahoo sold itself to Verizon for $4.48 billion this year. But the deal was nearly derailed by the disclosure of the breaches and $350 million was cut from Verizon’s original offer for the internet company. Yahoo was combined with AOL, another faded web pioneer that Verizon bought in 2015, into a new division of the telecommunications company called Oath.
