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Anti-OCR filtering spam

Posted by Michael Bloch in online world (Monday November 20, 2006 )

It certainly makes you wonder where the fight will end – who will emerge victorious and what the web will look like by that time. I shudder to think how much of the web’s oomph is sucked up by spam flying around the place. As mentioned previously, about 70% of the email that hits the servers of the hosting company I’m the Business Operations Manager of is spam.

Very little of the tens of thousands of spam items that hit our servers actually wind up in the inboxes of our clients; but when you start seeing these sorts of methods, it does make me cringe when considering the future of email, and as a marketer, even more so.

Related:

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Ah, the ingenuity of spammers never ceases to simultaneously amaze and frustrate me. As more companies begin to offer anti-spam software and services with OCR (Optical Character Recognition) features, spammers are now employing anti-OCR filtering tactics.

Spammers are beginning to use CAPTCHA style imagery to get past the good guys it seems. Captcha is an acronym for “Completely Automated Public Turing test to tell Computers and Humans Apart”, often used to prevent bots from signing up for services automatically, or exploiting forms for the purposes of spamming. So it’s a CAPTCHA strategy reversed.

Here’s a scaled down sample of what I’ve been seeing lately.


Sample of spam OCR detection avoidance

When these first started coming in a couple of weeks ago, they weren’t as complex – light backgrounds, very subtle text distortions and the usual blather of non-filter tripping garbage text underneath the image. Then the backgrounds became more complex and the wording on the images started to waver more. Had me a little puzzled.

At that point, I wasn’t aware of OCR based spam filtering, but knowing that professional spammers don’t do anything without good reason I started digging around some of the high end anti-spam filtering services and yep, it’s been in use for a while it seems.

Not only do some services offer OCR filtering, but also detection of umm.. let’s say adult images. It’s pretty ingenious stuff; but obviously not enough to deter the most dedicated spammers. The extra server overhead of OCR filtering on top of all the other filters currently in use by many companies must be shocking. Fighting spam has become somewhat a war of attrition.

It certainly makes you wonder where the fight will end – who will emerge victorious and what the web will look like by that time. I shudder to think how much of the web’s oomph is sucked up by spam flying around the place. As mentioned previously, about 70% of the email that hits the servers of the hosting company I’m the Business Operations Manager of is spam.

Very little of the tens of thousands of spam items that hit our servers actually wind up in the inboxes of our clients; but when you start seeing these sorts of methods, it does make me cringe when considering the future of email, and as a marketer, even more so.

Related:

Anti-spam filtering services

How spam and viruses wind up in your inbox



 

 
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