The file "getImg.php" took multiple HTTP GET parameters that would auto-download a modified image file if supplied with a link to an image through the "imgurl" parameter. The way it worked was that a hot image file (an image file that contained a payload) would be processed by the command line tool "ImageMagick" then accidentally execute arbitrary commands because it lacked sanitation. To specify a particular image format, precede the filename with an image format name and a colon (i.e. ps:image)... ... or specify the image type as the filename suffix (i.e. image.ps).