The rapid growth of cybercrime markets is making spam an even more attractive proposition than it has been in the past, according to a well-known researcher.

Matt Sergeant, chief anti-spam technologist for Symantec's MessageLabs unit, will offer a look at spam and the cybercrime economy in a presentation at next week's Gartner Security Summit in Washington, D.C. And the news isn't particularly good, he says.

"With the wide availability of email mailing lists, and with so many botnets for rent to carry them, spam campaigns have become appallingly cheap to launch," Sergeant says. "For about $10, you can send a million emails.

"The continued growth of spam traffic is entirely attributable to the rapid growth of the underground economy," he continues. "At these prices, you can launch a massive campaign that gets the smallest response, and yet still makes a profit. Why does spam continue to grow? Because there's still a lot of money in it."

In its May 2009 Intelligence Report, MessageLabs reported that spam levels had increased 5.1 percent over the previous month, accounting for more than 90 percent of all email traffic. More than half (57.6 percent) of spam traffic comes from known botnets; an emerging botnet called Donbot was responsible for 18.2 percent of all spam, the report says. And although much attention has been paid to large botnets, such as Conficker or Storm, more than 42 percent of spam originates from smaller or unclassified botnets, the researchers say.

Recently, MessageLabs has begun to track a single spam campaigns across multiple botnets, and the results are revealing, Sergeant says. "We can see that spammers will send out a short campaign on a botnet to evaluate it," he says. "We suspect that the spammer will choose the lowest-priced botnet for rent, and then test it to see the results. If they don't like what they find, it's fairly cheap and easy to find another botnet to try."

This ease of choice -- and greater price competition among botnets -- is largely the result of underground markets that allow spammers to window-shop and find the best deals, Sergeant says. Some spammers are beginning to specialize in reaching specific audiences, such as users of Gmail or AOL, and they choose botnets that help them reach those audiences, he observes.

But while spam is hotter than ever as a means of mass marketing, it is falling out of favor as a means of delivering malware, Sergeant notes. "The volume of malware sent directly to the user via email has dropped significantly," he says. "The most popular way of distributing malware today is through browser vulnerabilities that allow you to push malware out through Websites. You might put links to those Websites in a spam message, but the approach of sending malware as an attachment in an email is no longer considered to be very effective."

Aside from injection attacks and other Web exploits, malware distributors also are moving from email to next-generation media, Sergeant observes. "We're seeing a lot of spam and email going out via Twitter," he says. "Twitter breaks the trust model for Web links because it relies so heavily on URL-shortening systems. A lot of those systems are not trustworthy -- they can route you almost anywhere."

And despite numerous reports of bugs and attacks on social networking sites, such as Facebook, Sergeant believes the industry has only just begun to see "the thin end" of the social networking spam and malware spike. "There will be more -- we particularly expect to see blended threats that take advantage of social networks and the Web at the same time," he says.

With so many spam vehicles -- and so many spam messages being sent out each day -- you'd think end users would eventually get wise. "Sadly, that hasn't happened -- from what we know, the percentage of users that fall for spam messages hasn't dropped very much," Sergeant says. "It almost makes you lose faith in humanity. But a lot of spam is used to promote weight loss solutions, medicine without prescriptions, and that sort of thing, where you're looking for a gullible user anyway. For a lot of spammers, it's still working."

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