networkworld.com/news/2006/110806-image-spam
This spike in spam levels is a result of a new generation of viruses and zombies that can infect PCs more quickly and are harder to get rid of. In its October report, messaging security vendor MessageLabs says the spike is largely due to two Trojan programs, Warezov and SpamThru.
Others say a new breed of spam messages called image spam — messages with text embedded in an image file that evade spam filters, which can’t recognize the words inside the image — is responsible.
At North Shore-LIJ Heath System, a network of hospitals based in Great Neck, N.Y., with about 12,000 e-mail users, there’s been an 80% increase in spam received in the last 45 days, says system architect Steve Young, and most of it is image spam.
“On a scale of one to 10, I would rate image spam as an 8” in terms of how troublesome it is, says Paul Judge, CTO of Secure Computing. “This is because spammers have leapfrogged from hiding text within other text to now moving it to a place that is unreachable by most antispam systems.”