EBay Inc. came under pressure Thursday over a massive hacking of customer names, addresses and passwords as three U.S. states began investigating the e-commerce company's security practices.

Connecticut, Florida and Illinois said they are jointly investigating the matter. New York Attorney General Eric Schneiderman said eBay should provide free credit monitoring for everyone affected.

Details about what happened are still unclear because eBay has provided few details about the attack. It is also unclear what legal authority states have over eBay's handling of the matter.