Yahoo! data breaches
The Internet service company Yahoo! reported two major data breaches of user account data to hackers during the second half of 2016. The first announced breach, reported in September 2016, had occurred sometime in late 2014, and affected over 500 million Yahoo! user accounts. A separate data breach, occurring earlier around August 2013, was reported in December 2016. Initially believed to have affected over 1 billion user accounts, Yahoo! later affirmed in October 2017 that all 3 billion of its user accounts were impacted. Both breaches are considered the largest discovered in the history of the Internet. Specific details of material taken include names, email addresses, telephone numbers, encrypted or unencrypted security questions and answers, dates of birth, and hashed passwords. Further, Yahoo! reported that the late 2014 breach likely used manufactured web cookies to falsify login credentials, allowing hackers to gain access to any account without a password.