Service Pack 1 for AutoCAD 2013 is out. This update brings many bugfixes and new features that allow you to block AutoLISP program execution. Indeed, as I explained in this article, it is possible to write a virus using AutoCAD as a vector for the infection.
You can have a detailed description of these features on the blog Whithout a Net
To test, I created a small ZIP archive containing a drawing (Open me in the explorer.dwg) and an acad.lsp file. If you unpack the archive and then open the .dwg by double-clicking on it in the file browser, the code in acad.lsp will be displayed. Do not worry, I'm not doing anything dangerous, I just displays a message.
Note that this does not work if you open the drawing directly from your decompression software because in this case the .dwg file file is extracted separately from the acad.lsp.
You can download the zip here to test if your installation of AutoCAD is exposed to this type of threat.