It was the biggest known breach of a company’s computer network. And now, it is even bigger.

Verizon Communications, which acquired Yahoo this year, said on Tuesday that a previously disclosed attack that had occurred in 2013 affected all three billion of Yahoo’s user accounts.

Last year, Yahoo said the 2013 attack on its network had affected one billion accounts. Three months before that, the company also disclosed a separate attack, which had 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.