This. Is. Serious. Yahoo has revealed that ALL of its three billion user accounts were affected by the August 2013 data theft.
The number is three times the one billion accounts that Yahoo said were impacted last year. The data stolen included names, birth dates, phone numbers, passwords, and the security questions and backup email addresses used to reset lost passwords.
In a press statement, Yahoo pointed out that it has taken “action to protect all accounts, including directly notifying impacted users identified at the time, requiring password changes and invalidating unencrypted security questions and answers so that they could not be used to access an account.” The company also notified users via a notice on its website.