Spammers have figured out a number of ways to embed text into images — where anti-spam solutions based on text analyses can’t get to it. And as security vendors have begun building image spam solutions, spammers have created a series of random images for separate mailings that, again, simply won’t be flagged. Or they can put the text into multiple images in each mail. Or use obscure file formats.
Not only do the images elude anti-spam software, their malicious payloads are more likely to be launched by users. And they’re bandwidth- and storage-eaters; the average size of an image spam is 18 KB, compared to 5.5 KB for a text spam.
News Source : IT Business Edge