How to protect yourself online

Security experts say there are several steps you can take to protect yourself from hackers:

Check your credit report regularly to make sure stolen information isn't being used to open new accounts. That scenario is unlikely in the Citi case because the hackers didn't get enough information, but it's good to check anyway.

"Where consumers have to be very concerned is when information like their date of birth, their Social Security number, or their mother's maiden name is breached," says Tom Osherwitz, chief privacy officer at ID Analytics.

Vary the user names and passwords on your online accounts, and make sure to change any user names and passwords that match those in an account that may have been hacked.

Third-party services will monitor accounts established in your name and alert you to something suspicious. If you decide to pay for one, make sure it covers all three credit bureaus and tells you about all activity in a timely manner. Otherwise, it's not worth the money.

If you are the victim of identify theft, report it to the authorities.