• Categories designated for CAD related software have been eliminated.
  i.e. Block Managers and other CAD related utilities as they invariably
  are .EXE executable files.

• Lisp Routines section has been removed since malicious coding can be inserted. *
  AutoLISP-based Viruses

  An AutoLISP-based virus typically occurs via an AutoLISP file that runs
  automatically when a drawing is opened. Such startup AutoLISP files include
  acad2009doc.lsp: An Autodesk-provided file that runs every time a drawing is opened
  acad2009.lsp: An Autodesk-provided file that runs once when AutoCAD is launched
  acaddoc.lsp: A user-created file that runs every time a drawing is opened
  acad.lsp: An older-style file that runs once when AutoCAD is launched

• We have updated our system to automatically reject all .exe files.
  If a user attempts to upload an .EXE file at the end of the process they will receive
  a file rejected error message. The file will not be added to our database.

• The security of our FTP servers has also been reinforced.

To protect yourself:

Keep your antivirus current. (We like Avast and it's free).

Enable the macro virus protection in AutoCAD .*

Anticipating the potential for problem macros, AutoCAD software has long included
an option to warn you when opening a drawing or project file that includes embedded macros.
From that warning dialog box, you can disable the macros before they are able to execute.
The warning dialog box is enabled by default in AutoCAD; if, for any reason, this dialog
display becomes disabled, it can be turned back on by running the VBARUN command,
choosing the Options button, and checking “Enable macro virus protection.”
This setting will be saved in the current profile.

* Sources:

http://www.symantec.com/security_response/writeup.jsp?docid=2003-120513-5257-99&tabid=2

http://usa.autodesk.com/adsk/servlet/ps/item?siteID=123112&id=12903754&linkID=9240617

http://blog.jtbworld.com/2009/04/autocad-and-dwg-viruses-made-in-vba-or.html