After two weeks of investigation, Facebook announced additional details on Friday of how attackers carried out a massive breach of the social network that compromised accounts for tens of millions of users. The company downgraded its estimate of how many users had their access tokens stolen from an original estimate of at least 50 million to 30 million—and shed new light on exactly how an attack of this magnitude happened in the first place.

Get in-depth coverage of current and future trends in technology, and how they are shaping business, entertainment, communications, science, politics, and society.