[nso]

Ah yes. That one.
The hack works by detecting a certain pattern in the file

PHP Code:

        while($i = strpos($whole, 0x2C, $i+1))
        {
                if(strpos($whole, 0x00, $i-1) == $i-1)
                $c++;
        } 


This pattern may actually occur without there actually being a new frame. I only recently discovered this myself, and as far as I can see there is no foolproof way of doing this without the false positives.

Suggestion on this part would be highly appreciated. I know that you also could do a check for the string "NETSCAPE" in the header of the gif, but that won't suffice.
Does anyone know how an image processing application like, for example, Adobes Imagemagic (isn't that the right one?) seperate the frames?