I found this visitor trying to do something with some images on my site, but it is not clear exactly what the purpose of their coding was. The server logs showed:
67.83.122.nnn - - [25/Oct/2010:19:23:09 -0400] "GET /mammals/deer/url(data:image/png;base64 following this was a ton of obfuscated code. They were served 404s for this activity.
Does anyone know what they were trying to do? Should they be blocked?