The Yahoo internet giant announced Thursday that user information in at least half a billion accounts was hacked in 2014.
The company said in a statement that personal data such as email addresses, names, birth dates, passwords and phone numbers, as well as security questions, were all compromised by an unidentified “state-sponsored actor.”
Such data is also linked to many other systems, including financial services, and often the personal data of friends and family, a New York-based law enforcement official who requested anonymity, noted.
Users are being warned to review their accounts for suspicious emails and other suspicious activity. The company said it is working with law enforcement.