It's Halloween season, so permit me to scare you: Your credit card number, which you take such great pains to protect, may well be available online, to anyone who wants to look it up!

I have Steve Orr of the Rochester Democrat and Chronicle to thank (or blame) for this alarming news. In a recent column, he described how he himself successfully looked up other people's credit card numbers.

"My search began last week after I read a story on a business-news Web site in which the authors explained how to find credit-card numbers on the Net. The authors carefully laid out their methodology, but, after some reflection, I've decided not to describe their method or even to point you to the news story. But I can tell you that their method, which involves online searching and likely is well-known to hackers, works quite well. I quickly found hundreds of stolen credit-card numbers, and could have found thousands more. Many cards were expired, but many others were not."

How can this be? Orr explained, "The authors of the Web story said they had found mom-and-pop Web merchants who'd carelessly left their ordering-and-shipping data unprotected. I found no such merchants. But I did find plenty of apparent hacker sites storing stolen data...."

The news gets a bit worse, because there's no way that you can completely protect yourself against this. Still, you can take a few sensible precautions, such as only shopping online at reputable retailers, after looking up what security protections they offer (most such sites have links leading you to more information on this). Reputable retailers include the likes of (NASDAQ:AMZN), Best Buy (NYSE:BBY), and (NASDAQ:OSTK), but perhaps not Dwayne'sWorld-o' or

There's more help on the way, too. According to information from Visa, "the financial services industry is developing additional safeguards to help prevent online fraud from occurring. New authentication measures enable you to confirm that you are the authorized user of your card when shopping on the Internet. One such solution -- Verified by Visa -- allows you to register your Visa card with a participating bank, then create a single password that you can use during the checkout process at participating online merchants. The password is your way to identify yourself online, just like signing a sales receipt at the cash register. Contact your financial institution to learn if your card is eligible for this service."

Still, as Orr notes, ".not all problems stem from online shopping. Some of the worst identity-theft cases arise when crooks manage to steal an entire customer database."

Consider routinely checking your credit report for signs of shenanigans -- learn how to check your report in our Credit Center.

Longtime Fool contributor Selena Maranjian owns shares of