Wednesday, November 08, 2006

Ransom note spam

Back in January I added a trick called The Small Picture to The Spammers' Compendium, and in August I updated The tURLing Test trick with an example of its use in image-based spam.

The Small Picture consists of sending individual letter images attached to a message. These letter images are then used to display a message and break up words that the spammer might think a spam filter would find suspicious. Here's an example of The Small Picture where certain letters (look carefully!) are formed using images rather than text:



The tURLing Test consists of disguising a URL by breaking it up and then explaining to the user how to type in the URL, thus proving that a human is reading the spam not a spam filter. This is done with URLs so that URL blacklists are bypassed. Here's an example of that from an image-based spam:



Now comes a combination of the two, that deserves the name 'Ransom Note Spam': it combines both The Small Picture (the letters are individual images attached to the spam) and The tURLing Test (the URL is made up of letters in the images):


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