In just half a year, the problem of image spam has become widespread enough to represent 35 per cent of all junk email, according to vendor F-Secure.
Spam originally used basic text captured in a GIF image to bypass standard dictionary-based content filters, but this has now evolved into image spam. This new type of junk message features the use of random nonsensical text messages sampled from legitimate web sites between the hard-sell of products.
Image spam also causes problems for corporate networks because of the amount of bandwidth it takes up.
'Image spam is a serious and growing problem. It also is taking up 70 per cent of the bandwidth bulge, on account of the large file sizes every single one represents,' said Mikko Hypponen, chief research officer at F-Secure.
The time taken to filter out and destroy spam also represents a significant burden on IT staff and personnel in organisations.
A typical botnet - a network of PCs remotely controlled by spammers - can send 160 million messages in just two hours. And last year, botnets raised the volume of spam in circulation by 30 per cent. For businesses, often the target of spam attacks, that figure was 50 per cent.
'We will never rid ourselves of spam until people stop buying the products advertised in these mails. Spam obviously works, otherwise it would not be so prevalent,' said Hypponen.
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