New investigation into Yahoo 2013 data breach reveals that all 3 billion user accounts were compromised

Verizon-owned Yahoo this week revealed to users that the scale of its widely covered 2013 data breach is much bigger than previously estimated.

In 2013, a hack targeting Internet giant Yahoo ended up exposing account information of upwards of 1 billion users – a conclusion the company came to after years of investigations – including names, email addresses, hashed passwords, birthdays, phone numbers, and even “encrypted or unencrypted security questions and answers” in some cases.

Yahoo keeps an updated record of the breach on the Yahoo 2013 Account Security Update FAQs page, at https://yahoo.com/security-update.

A new investigation into the hack, however, has uncovered that every single one of the 3 billion Yahoo accounts on file was, in fact, compromised. In a statement this week, Yahoo said:

“Subsequent to Yahoo’s acquisition by Verizon, and during integration, the company recently obtained new intelligence and now believes, following an investigation with the assistance of outside forensic experts, that all Yahoo user accounts were affected by the August 2013 theft.” (emphasis ours).

Yahoo offers no numbers, but the company”s database stood at around 3 billion accounts at the time it was breached.

Stolen user account information did not include passwords in clear text, payment card data or bank account information, the investigation further indicates. Yahoo is working closely with law enforcement still, so additional details may yet be uncovered.

“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.”

Acquired by American telco giant Verizon for $4.5 billion earlier this year, Yahoo is “roommates” with AOL under a new business group called Oath.

Oath describes itself as a global leader in the digital space with the mission to “shape the future of media.”