From The Naked PC issue #5.07...

Fighting Spam - Part 3

by Dan Butler
March 28, 2002

So far you've learned how to hide your real address, when and when not to respond to spam that arrives in your box, and a few ways spammers get your name in the first place. This time you'll learn about the "dictionary" attack, one of the more common ways that spam is sent.

In a dictionary attack the spammer just sends email to every address in a dictionary of commonly used email addresses. Actually two dictionaries are used. One is commonly used user names. The other is known domain names. So you might have dan, danny, daniel, etc. in one dictionary and aol, netscape, mindspring, etc. in the other. The system then matches the names to the domains and blasts the spam out. We are not talking about hundreds of emails sent but rather hundreds of thousands or more.

The spammer is forging the information that identifies what system and who sent the mail. So any mail returned undeliverable falls into a black hole. You see, they really don't care if the mail bounces or not. It's a numbers game to them.

A spammer doing this is hoping a percentage of people reading the message will respond to their message. With the email headers forged you can't just reply. Instead you'll find a link to a different Web site or a phone number to call to order. If you decide to purchase from one of these emails you are a braver person than I. Personally I feel that someone who will lie to me via a forged email is not someone I want to do business with.

The bottom line? It often isn't worth your time trying to figure out where the spam originated. A true spammer is moving from system to system to hide their evil ways. The casual spammer does need some educating but you can be sure that any responsible ISP will be having a chat with the person soon.

Now that you know about the dictionary attack you can understand why some addresses get more spam than others. They are more likely to be in a dictionary list. It's really a kind of catch- 22. You can make your address difficult to spell and remember to avoid the dictionary attacks, but then your friends will have a dickens of a time emailing you. Plus you have no guarantee that what you choose isn't in one of the dictionaries the spammers use.

The bottom line: remember rule #1. Never respond to a spam to remove yourself from their list. Honoring this rule will do more to protect your account than anything else. Then use the filters your email program has available. Next time I'll show you some simple ways to use your filters and I'll point you to some additional resources.

You can reach Dan Butler at:
mailto:danbutler@TheNakedPC.com

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