PDF Based Image Spam
About three weeks ago we started talking about a shift in image based spam tactics where we were seeing a couple of new tactics in image spam. One tactic was spam images were being hosted by free image hosting services and being linked to within the message body. The second was the body background attribute being used to pull down images remotely and render within the message and look like traditional image spam.
We are now seeing the next wave of this where the image is being embedded within a PDF file. Although PDF based spam is not new (it originally reared its head back in 2004, but never caught on).
This is an interesting new tactic because even utilities that exist which convert PDF files to text would not help in these situations because those tools would not perform OCR functions on the image (OCR tools on image spam have been largely useless for about a year now anyway).
No stats yet on volume numbers associated with this new tactic, but we'll be collecting those and I will make those available in the coming weeks.
Posted by smasiello at 3:10 PM | Link | 0 comments
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