Yahoo has increased the number of user accounts affected by a 2013 data breach, which has been described as the largest in history. The embattled company said that all three billion of its accounts were hacked, tripling the number of affected accounts from the previously estimated one billion.
On December 14, 2016, Yahoo announced that based on its analysis of data files provided by law enforcement, the company believed that an unauthorized party stole data associated with certain user accounts in August 2013.
The stolen user account information included names, email addresses, telephone numbers, dates of birth, hashed passwords (using MD5) and, in some cases, encrypted or unencrypted security questions and answers.
The new disclosure comes four months after Verizon acquired Yahoo’s core internet assets for $4.48 billion. Yahoo is part of Verizon’s digital media company, which is called Oath.
Yahoo said it is “closely coordinating” with law enforcement on the matter, and continue to enhance its systems that detect and prevent unauthorized access to user accounts.
“Verizon is committed to the highest standards of accountability and transparency, and we proactively work to ensure the safety and security of our users and networks in an evolving landscape of online threats,” said Chandra McMahon, Chief Information Security Officer, Verizon. “Our investment in Yahoo is allowing that team to continue to take significant steps to enhance their security, as well as benefit from Verizon’s experience and resources.”