Researchers at Kaspersky Lab, one of the leading antivirus makers, have recently discovered a new form of spam. It looks like spammers have finally figured out how to evade advanced spam filters. They started sending bogus e-mails with no text or static images that filters analyze. Instead, these letters contain animated GIF images with two or more frames. Such images can be displayed by any web browser or e-mail client.
According to Kaspersky Lab, “animated spam has between two and four frames; out of these, only one of them actually contains significant information about the goods or service being promoted. The remaining frames simply act as background, or contain other pictorial elements. The main frame is displayed to the user for up to 10 minutes, while the remaining frames will be displayed for mere tenths of a second.”
Supposedly, a larger part of simple spam filters will not detect animated spam, as such tools examine message structure, search for specific keywords in text, etc., but don’t analyze any images. Nevertheless, this doesn’t mean that animated spam cannot be blocked. Powerful spam filters as well as less advanced tools inspect other e-mail attributes as well, and therefore can block typical spam of any form. However, well-made animated spam has a great potential to slip through a net.