One million Americans have been swindled and they may not even know it.

The Federal Trade Commission announced Monday that it is cracking down on an international ring of scammers who managed to steal more than $10 million from Americans. The scammers billed more than 1 million consumers for small amounts of money using a series of fake virtual businesses. The secret to the scam is that each of these consumers was charged a negligible amount of money on their credit cards.

“Most consumers either didn’t notice the charges on their bills or didn’t seek chargebacks because of the small amounts – charges ranged from 20 cents to $10,” the FTC noted in a statement this week. Those customers who did notice a false charge and tried to call the company were unable to get in touch with a real person. As far as the FTC can tell, the scam seems to date back to sometime in 2006, and over that time, these small charges have added up to a massive $10 million haul.

The FTC has thus far identified 16 “sham companies” who posed as legitimate institutions as part of this scam, including ARA Auto Parts Trading LLC and Hometown Homebuyers LLC. The culprits were meticulous in their execution of this scam. They began by targeting consumers who had already been the victims of identity theft and made sure to only charge each consumer once so that neither they nor their credit card companies would get suspicious. But that was just the first of many precautions.

“The defendants also cloaked each fake merchant with a virtual office address near a real merchant’s location, a phone number, a home phone number for the ‘owner,’ a Web site pretending to sell products, a toll-free number consumers could call, and a real company’s tax number found on the Internet,” the FTC reports.

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To facilitate the process, the scammers also hired at least 14 “money mules” who were responsible for opening up bank accounts in countries all over Europe and Asia.

For the time being, the FTC has successfully managed to freeze the assets of the 16 fraudulent companies and to raise awareness for the scam, but many members of this scam network are still out there.

Ultimately, this scam is proof that consumers are less diligent than they should be in reviewing their credit card statements for false charges. According to Wired, just 10% of consumers affected by this scam took steps to contest the charges. Granted, some of these charges were for less than a dollar, but if there’s one lesson to take from these scammers, it’s that a few dollars here and there adds up to a lot. Be sure to review your credit card statements carefully each month and considering signing up for services like that allow you to keep track of your expenditures in real time.

This scam also shows how easy it is to create a company that appears legitimate. Before you do business with any company online, be sure to look at our checklist of ways to make sure it’s a reputable business.

—For a comprehensive credit report, visit the Credit Center.