Image Spam Beating Filters Causes High Spam

Spammers are developing new methods to evade filters, but that should not stop users from preventing them to bombard inboxes, reports Rob Buckley, freelance editor and journalist. SCMagazine published this on May 23, 2007.

Instead of constructing text-based e-mails, spammers these days embed their products in the form of images. In this way, a normal spam filter fails to recognize such image spam allowing the message to pass.

For this reason, image spam accounts for a significant proportion of the entire spam traffic. What this amount is has been in debate by various security firms. According to security vendor Marshal, the figure is almost 56% of total spam while SurfControl puts it between 25 and 40% and F-Secure and Sophos estimate it at around 35%.

Security firm Symantec thinks that image spam is chiefly responsible for the overall increase in spam mails over the past few years. In just one year (2006), image spam has risen from 5% to 40% of total spam. The reason behind this is very simple. As stronger and stronger anti-spam filters emerge that typically pick up the "word salad", a part of spam mail text, spammers have begun to use images that filters find difficult to detect and thus easier to pass through to the inbox.

Many commentators dismiss the estimated spam figures as exaggerated. For instance, Mark Sunner, chief security analyst at MessageLabs, said that spam is approximately between 10 and 20%, as reported by SCMagazine on May 23, 2007. Some vendors calculate a scare mongering proportion of two-thirds of all spam, Sunner illustrated.

It is not clear if the change indicates a pattern away from non text-based spam or is just a deviation. There are many new and evolving trends and methods that could announce a future comprising of junk e-mails.

Image spam mails arrive in massive bulks, Mark Sunner added. Botnets, which are networks of compromised computers, send these bulk spam. spammers control these botnets thinking that some of those e-mails will defeat spam filters. Measuring spam during a single wave of e-mails could show a higher percentage of this attack than it really is.

Related article: Image Spam Set to Hit Worldwide PCs Back

» SPAMfighter News - 6/4/2007