Yahoo revealed on Wednesday that more than 1 billion user accounts were breached in August 2013. The hack appears to be separate from the 500 million account breach that Yahoo reported this September, and it follows a history of security problems for the digital company.
Bob Lord, Yahoo's chief information security officer, wrote in statement that the company has "not been able to identify the intrusion associated with this theft."
He also stated: "The stolen user account information may have included names, email addresses, telephone numbers, dates of birth, hashed passwords (using MD5) and, in some cases, encrypted or unencrypted security questions and answers."
Law enforcement alerted Yahoo about the massive hack, and its data has been examined by third-party forensic experts. The data does not appear to include financial details or payment information.
Affected account holders have been notified, said Yahoo, which is in the process of being sold to Verizon. Whether today's news impacts the sale will be worth watching.