NEW YORK (AP) – Russian hackers working with Russian spies didn’t crack Yahoo security all at once.
Instead, according to an account offered by U.S. officials, they methodically made their way deeper into Yahoo’s network over the space of months – maybe years. That allowed them to forge technological skeleton keys that would unlock many Yahoo accounts, steal personal information and then use that data to break into other email services used by their targets, U.S. officials said in announcing charges against four Russians .
The hackers’ primary targets were Russian and U.S. government officials, Russian journalists and employees of financial companies and other businesses. But the attackers also used access to Yahoo’s network for financial gain, according to Wednesday’s indictment.
The severity of that breach, the second worst in internet history, was most likely magnified by the fact that it took some two years for Yahoo to disclose the initial attack. Had Yahoo taken more aggressive steps – for instance, asking users to change their passwords, or even expiring the passwords and forcing users to enter new ones – it might have prevented some of the damage.
Here’s a look at how the breach occurred, according to U.S. officials.