• With: Garrett Tenney, David Kennedy

    This is a rush transcript from "Your World," December 19, 2013. This copy may not be in its final form and may be updated.

    ERIC BOLLING, GUEST HOST: Merry Christmas. You have been hacked.

    Target warning shoppers that some 40 million credit and debit card accounts may have been hit by thieves.

    Garrett Tenney is outside a Target in Chicago.

    Garrett, big story, big stuff.

    GARRETT TENNEY, FOX NEWS CORRESPONDENT: Eric, if anyone -- if anyone at home shopped at Target between November 17 and December 25 (ph), which includes Black Friday, they could be among the 40 million shoppers who had their personal information that was stolen by these thieves.

    Now, how these thieves did it, that magnetic strip on the back of the card, that's where all of that personal information contains, with that kind of data, they can be able to steal identities, create counterfeit credit cards, and potentially they can get cash from ATMs as well.

    Now, the good news is, Target says it has identified and resolved this issue. Customers we spoke to today, though they said, as long as it's been taken care of, that's what they're most concerned about.

    (BEGIN VIDEO CLIP)

    UNIDENTIFIED FEMALE: It's a little scary, but I think it can happen to any big retailer.

    UNIDENTIFIED FEMALE: I think if there's something wrong, the bank will take care of it. I'm not overly concerned, so just check the credit report eventually, and it should be fine.

    UNIDENTIFIED MALE: It might be a little bit of Target's fault, but there's back-end technology companies that are handling that data once you swipe that card. So there's probably a lot of blame to go around.

    UNIDENTIFIED FEMALE: I'm on the plus side of the glass is half-full, and so I wouldn't let it concern me.

    (END VIDEO CLIP)

    TENNEY: And for those customers that might be a little bit more concerned, though, Target is encouraging them to keep a close eye on their bank account statements for any unusual or suspicious activity over the next few months.

    But security experts say that should last even through the next few years. Target has also set up a hot line for anyone to call if they do believe that they have been affected by this security breach -- Eric.

    BOLLING: All right, thank you, Garrett.

    As if holiday shopping isn't stressful enough, now we have to worry about in-store hacking.

    David Kennedy is a well-known hacker and has some tips to keep your information safe.

    Very quickly, Dave, before we get to the tips, does this sound like an inside job to you?

    DAVID KENNEDY, FOUNDER, TRUSTEDSEC: Well, it's too early to tell.

    But the sophistication that you had on this type of attack, it looks like they actually targeted the point of sales systems, where you actually swipe your card, and that's both debit and credit. It looks like they hit that on a wide scale. So, it definitely seems really sophisticated. Could have been an insider or it could have been somebody that spent a lot of time developing this attack and hitting it at the right point, which is their busiest season -- season.

    BOLLING: All right. All right. Let's go through a few of your tips.

    Number one, the first that you said, cancel your credit card, I guess, if you shopped at Target during that period, but, boy, that -- that seems aggressive, no?

    KENNEDY: Well, it's a lot easier than you think.

    I mean, all you need to do is call your bank up and say I think my card was stolen or it was compromised. They will send you a new credit card, usually within the next two or three days. And you have it and you don't have to worry about it.

    The thing is with canceling your credit card is now you know for sure that someone can't actually maliciously -- maliciously use your credit card. You don't have to monitor it. It makes it a lot less hassle for a little bit of up-front work that you do.

    BOLLING: OK. Now, the next is, change your -- change your pin, your security code?

    KENNEDY: Yes.

    When you use a debit card, usually, those debit cards don't ever change. And so, you know, when you -- if you use your debit card at -- at Target and you actually entered your pin number into there, those were potentially harvested as well. So you definitely want to make sure that you change your debit card, even though your debit card can be used conjunctively with debit -- debit and credit. So, definitely recommend changing it.

    BOLLING: And, also, you say monitor your activity on a daily basis?

    KENNEDY: That's right.

    When you know that you have experienced a breach of your personal information, your credit card data, you definitely want to monitor it. There's a lot of great services out there that can also do it for free, that monitor your credit, monitor for things being checked out that can do it for you.

    But check your bank accounts. Make sure there isn't any fraudulent charges. And as soon as you notice a fraudulent charge, contact your bank immediately. They will cancel your card and refund you that cash. And then you get a new card sent in the mail within a day or two.

    BOLLING: All right. And the last one, consider a virtual wallet.

    What is a virtual wallet?

    KENNEDY: Virtual wallets are a really cool concept.

    Google Wallet is an example of that. PayPal also has them. And really it's kind of a temporary credit card number that you can use. And PayPal does a one-time credit card number where basically you use a credit card once and then it changes the number again. So you never have to worry about going to multiple retail stores and worrying about your credit card being stolen.

    If you look at Target, it's just one instance. This can happen -- this can to anybody. And so using one-time credit card numbers or getting notifications every time that there's some sort of charge being put on your debit card or credit card, those are things that you can do to make it much easier for you.