Spammer using Graphical Steganography

[Damien Miller]

On Mon, 23 Oct 2006, Bill Stewart wrote:

> Spammers have been including images in their email to evade anti-spammers.
> Anti-spammers have been using OCR to identify spammy words in images.
> Spammers have recently come up with tricks to work around OCRs,
> by doing steganography with animated GIF images.
> One approach they're taking is to build the real image progressively,
> first drawing a background, then drawing parts of the image
> (one spammer uses transparent pixels to do parts of it, showing dark parts of
> background),
> then waiting a long time and drawing a blank page in case anything's checking
> the final image.

IMO this isn't stego, more like a CAPCHA.

-d


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