NEW YORK (MONEY Magazine) - A crook has two advantages: The rise of fast credit and the easy availability of the information he needs to pretend to be you.

The first thing anyone you do business with wants to know about you is: Are you good for it? Lenders, department stores or cell-phone companies can get your credit information in moments with only a whiff of detail about you, explains consumer activist Ed Mierzwinski of U.S. Public Interest Research Group in Washington.

Then it's up to them to verify that you are who you say you are and, let's face it, some have little incentive to probe deeply.

Result: If a bad guy knows enough about you, and your credit score is reasonably good, there soon could be a half-dozen accounts in your name, with the bills being sent to an address you've never heard of.

Your Social Security number, of course, is one of the most important things to protect.

"It's like the key to the castle," says John Pironti, a security consultant for Unisys. Too bad thousands of people can easily see it. DMVs and county courthouses have it; so do employers, health insurers and colleges. Small-time thieves can start their hunt using an Internet search for online public records or simply digging through your trash.

Big data heists require more organization, but not necessarily "WarGames"-style hacking. Criminals often prey on human trust to get people to unlock secure data. ChoicePoint actually sold its files to people posing as legitimate businessmen. And selling your Social Security number, by the way, is in many cases perfectly legal.

Making matters worse: Once your data gets downloaded, the Internet makes it easier for criminals to buy and sell it around the world, from gangs in Nigeria and Eastern Europe to boiler rooms in California.

"They form almost a type of crime family, called Web mobs, set up like the old Mafia," says Matt Ziemniak, an analyst at the National Cyber Forensics and Training Alliance. "They know each other only online except at the very top."

Get the picture? The toothpaste is out of the tube. Tons of people have data about you. Tons can use that data. You don't know who most of these people are.

Most will be honest, but all it takes is a few crooks. The remedy isn't more locks and cops to keep your data safe. The key is giving you more control over how your data can be used.

ID Theft: Your data should be yours

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