(CBS)  Someone's identity is stolen every three seconds in the United States.

Crooks are making billions buying and selling identities, and most consumers have no idea their information is out there, up for sale.

In the underground world of identity theft, credit card, bank account and Social Security numbers are being bought and sold by thieves around the globe, reported Early Show Consumer Correspondent Susan Koeppen Monday in the first of a three-part series, "Early on the Case: Stolen Identities."

"(Through) the selling of (personal) information en masse, they can make millions of dollars in one transaction, in terms of who they go after. Really everybody is exposed," Tom Rusin, CEO of Affinion Group, told Koeppen. Affinion helps safeguard consumers' identities.

More than 8 million Americans fall victim to identity theft each year, and many don't know their information is being offered on the Internet in chatrooms run by criminals.

A credit card number alone could be worth about $1.50, Rusin says. A name, address and social security number? Probably between $10 and $12.

Affinion's Dan Clement took Koeppen inside several chatrooms.

"I can't believe this is going on," Koeppen remarked. "The average consumer has no idea that people are sitting at computers and doing this sort of thing."

"No," Clement replied. "It's like the commodities market. It's just a different commodity. It's not real commodities, it's people's personal information."

In one, he pointed to identity thieves, security companies like Affinion, and law enforcement. "Everybody in there is kind of a fly on the wall, watching to see what these guys (the thieves) are doing," Clement explained.

Pointing to one entry, Clement said full login info for a Wachovia account with $11,000 in it was up for grabs. The account, he said, was sure to be liquidated, without its owner having a clue it was happening.

Koeppen says they "found entire personal profiles for sale, including names, addresses, phone numbers, credit card information, Social Security numbers, even mothers' maiden names.

One such profile belonged to Kellie Griffin, a working mom from Shreveport, La., who was shocked when Koeppen clued her in.

"My jaw dropped when you told me why you were calling," Griffin told Koeppen.

Griffin says she spends hours a day working on her computer, but she has no idea how someone got so much of her information.

"It's amazing!" Griffin exclaimed.

Griffin says she thought she'd been doing everything right to protect herself, and now she wonders, "What else do they have? Do they know what I look like? Do they have a copy of my driver's license? I don't know what else they have, and I don't know what they've done with it."

In one of the chatrooms, Clement and Koeppen pretended to be a thief pitching two cards.

Within five minutes, the cards began getting some bites from would-be purchasers "checking it out. They're trying to see what the balance is on the card," Clement said.

And within 10 minutes, the balance on both cards was nearly depleted.

"It's like throwing tuna to the sharks," Clement said.

Koeppen and Clement even struck up a conversation with a scammer who had credit cards for sale.

"Shadow Girl" was trying to sell them credit cards for $6. But Clement "negotiated" and go her to offer four cards for $16.

To protect yourself, Koeppen says you could: