Image spam slips through filters

Posted on Tuesday, September 05 2006 @ 3:49 CEST by Thomas De Maesschalck
Image spam is increasing rapidly, according to anti-virus lab AV-Test this type accounts for about a third of all spam today. The worst thing about this is that spam filters can barely filter this type of spam.
'In this form of spam, text is included in the image and then sent on. Most spam filters are designed to analyze text,' says Marx. 'But they are powerless when it comes to images.'

Olaf Pursche, a security expert for the Hamburg-based magazine 'Computerbild' (Computer Image), has also noticed the jump in spam. 'Many spam filters still can't screen out image spam. That means more unwanted mail in peoples mailboxes.'

The spam filters are thrown off by the variety of the e-mails. 'The pictures are generated so that every e-mail sent is slightly different,' says Marx. This is achieved by changing the size or formatting of a picture. Even a few altered pixels can let an e-mail sidestep a filter.
More details at Monsters and Critics.

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