Yahoo has detailed a new security breach of more than one billion user accounts, TechCrunch reported.
The breach took place in August 2013 and is separate from the “500 million account hack” which was reported on in September.
Yahoo’s chief information security officer Bob Lord said they have not been able to determine how the data was stolen.
“We have not been able to identify the intrusion associated with this theft,” he said.
“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.”
Yahoo said it will notify affected users about changing their passwords.