Thursday, February 11, 2010

Captcha - now even the spammers use it

Like everyone I know I have a Spam filter on my email, unlike many people, some of my real mail looks a bit spammy to the filters so I always need to check my spam folder before deleting.

Over recent weeks I've noticed quite a few spam emails that contain no text at all, just a graphic like the one I'm displaying (After removing their website) -->

There's some interesting things about this spam.

  • It's absolutely minimal. The headers in the email contain almost nothing and the body of the email contains only the image.
  • There isn't even a link, which is why the image tries to get the user to manually enter the spammer's URL.
  • The image is low quality and distorted -- probably to try and defeat optical character readers.
  • It still doesn't work. Google's spam filter (and I assume other major filters) detect it with perfect accuracy. As they keep coming, I can only assume that sufficient minor filters don't.
The really ironic thing about this spam though is the apparent use of captcha. So many spammers use robots to leave their ads on bulletin boards, forums, blog comments and more that all these resources now make us decode distorted images (captcha) before we're allowed to leave genuine messages. Not only have the spammers worked hard to "improve" their software to defeat captcha but now they are trying to use it to defeat the guardians of our in-boxes.

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