Spam on the rise with new breeds

If you're like me, each morning you greet an e-mail inbox stuffed with a new breed of fiendishly clever spam that somehow manages to elude your spam filters.

Earlier this year we thought the good guys were winning the war against spam. Back in January, I talked to spam fighters who were claiming victory in the spam wars. One company told me that the volume of spam had stopped growing at double-digit rates for the first time.

But that may have changed. Researchers and IT managers are now complaining that spam levels have risen significantly in recent months -- some organizations have reported increases as high as 80 percent. Overall spam volume has increased 67 percent since August 2006, according to Barracuda Networks, an enterprise security appliance vendor.

So what's changed? How are spammers managing to sneak their messages back into your inbox? And what can you do to protect yourself?

New and Improved Spam

Spam used to be strictly text based and commercial in nature, touting herbal remedies, linking to porn sites, and coming from average-Joe spammers looking to make some extra money.

Spam fighters were able to block this type of spam based on key attributes, such as words and phrases typically found in spam. They could also block e-mail that came from a known spammer, or filter spam based on the links that the messages contained. If an e-mail contained links to a porn site, for example, then a filter might reasonably guess that was spam.

The new breed of spam manages to evade filters because it contains no suspect words, is sent from hundreds of thousands of different PCs, and includes no links. How does it work?

The new spam evades traditional spam filters because it doesn't include any text -- instead, it uses an image embedded in the body of an e-mail to deliver its message. This image includes text that displays the spammer's message. But to make it hard for spam filters that may use optical character recognition technology to scan and read the text in the images, spammers are getting sneakier. They're sending pictures with textured backgrounds or various colors to throw off the filters. They're also varying the font for each letter of the text.

This way a spam filter can't tell an unsolicited stock tip from a holiday picture of the family.

Image spam currently accounts for up to 40 percent of incoming e-mail, according to McAfee Avert Labs. A year ago image spam accounted for less than 1 percent of the total spam received, the company reports.

Pump-and-Dump Spam