According to the Internet Security Systems (ISS) “Frequency” blog, image spam is making a comeback. A few years ago, we heard a lot about image spam, which was a clever way to trick spam filters by sending images of text, rather than the text itself. Image spam declined substantially by 2008 to the point where it was only about two percent of all spam–but it’s baaaaack!

ISS reports a rebirth of image spam, with a spike in March of this year where it reached five to 10 percent of all spam; and in April, it hit 15 to 22 percent. So why are spammers revisiting an old tactic? Peculiar. The new image spams don’t use any new groundbreaking technology, and most spam filters will be able to block them easily. The only difference is that the older, first wave of image spam back in 2006 and 2007 focused on stock trading and pump-and-dump scams. Today, stock scams aren’t going to get a lot of traction because of the economic crisis, instead, most of today’s image spams are pharmaceutical.

One possible explanation is that the spammers realize that their URLs are already in most antispam databases, and they are obscuring those URLs in the image to avoid being picked up by filters. Many of today’s image spams do not contain clickable URLs. Or maybe, just maybe, spammers have just run out of new ideas!