Companies will have to adopt a new approach to ridding corporate communication systems of spam as spammers switch to using images, says a Cape Town-based security company.
"Instead of text- or HTML-based messages, spammers are now sending spam in the form of embedded images, making it almost impossible to detect the message as spam without dramatically increasing the false positive rate," says Brett Casey, CEO of Securicom.
This form of spam is able to bypass most conventional detection methods, which identify certain patterns or signatures within an e-mail to determine whether it is suspect or not, explains Casey.
He says even if anti-spam filters identify images as spam, there are a wide variety of ways spammers can change images to change the structure of the message to make it undetectable.
According to Casey, up to 40% of spam is already image-based. This equates to around 16 billion image-based spam messages being sent around the world each day.
"In addition to its nuisance factor, administrators face the problem of slow-downs as their systems struggle to cope with spam messages that average around three times the size of text-based spam," he comments.
Casey advises that companies use a managed service that will prevent e-mail from reaching the network. He says the managed service provider blocks incoming spam outside a company's firewall, thereby reducing unnecessary consumption of bandwidth and storage.
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