Spam gets a new image: combating graphical junk mail

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Spam – we all get it, we all hate it (right?). And it’s continually evolving to keep a step ahead of whatever filters our mail software and ISPs put in place.

One of the current favourites is image spam. The whole message is a graphic, so there’s no text in the email message for filters to work on and check for ‘junkiness’.

Unfortunately, it’s generally still very human readable.

You could simply choose not to trust any image that comes in a message on its own, but you’d run the risk of discarding legitimate email with images that you actually want to receive.

Barracuda Networks have been working on the problem, and have come up
with software that combines junk-mail filtering with OCR (Optical
Character Recognition) technology and fingerprint analysis to work out
whether an image is junk or not.

They claim a high success rate. Normal email programs can’t read text
embedded in images, but Barracuda’s software can. Fingerprinting is
also used – keeping a database of known spam images and
cross-referencing portions of an image with that to weight images on
how likely they are to be spam.

Of course it won’t be long until the spammers decide to use something
more evasive. For example, the whole reason captcha’s (those irritating
graphics with skewed text and numbers on a patterned background used to
validate humans online) are supposed to work is that machines can’t
read them. You know where this is going…

Still, it’s another weapon in the continual fight against email crap.

(Via Silicon Republic)

Andy Merrett