Yahoo says hack hit half a billion users

Yahoo said that a massive attack on its network in 2014 allowed hackers to steal data from half a billion users and may have been “state-sponsored”.

Yahoo, which confirmed details of the breach months after reports of a major hack, said on Thursday that its investigation concluded that “certain user account information was stolen” and that the attack came from “what it believes is a state-sponsored actor”.

“Based on the ongoing investigation, Yahoo believes that information associated with at least 500 million user accounts was stolen,” said a statement by the US internet giant in what is likely the largestever breach for a single organization.

“Yahoo is working closely with law enforcement on this matter.”

Earlier this year, a report quoted a security researcher as saying that about 200 million accounts may have been accessed and that hacked data was being offered for sale online.

Yahoo said the stolen information may have included names, email addresses, birth dates and scrambled passwords, along with encrypted or unencrypted security questions and answers that could help hackers break into victims’ other online accounts.

While there is no official record of the largest breaches, many analysts have characterized the Myspace hack revealed earlier this year as the largest to date, with 360 million users affected.

Computer security analyst Graham Cluley said the stolen Yahoo data “could be useful ammunition for any hacker attempting to break into Yahoo accounts, or interested in exploring whether users might have used the same security questions/ answers to protect themselves elsewhere on the web.”