If SECURELOAD system variable (introduced first in AutoCAD 2014) is activated (set to 1) you may see a dialog box like below. If you are not sure the executable file can be trusted do not load it.
Dialog box text as below:
Security - Unsigned Executable File
The publisher of this executable file could not be verified and the file is not located in a trusted folder. What do you want to do?
Publisher: Unknown Publisher
Date: 08/26/2016 17:06
Make sure that this executable file comes from a trusted source and is located in a trusted folder.
[Always Load] [Load Once] [Do Not Load]
How do I decide what files to load?
But what if you have selected Always Load and later change your mind what can you do?
There is no way in OPTIONS to do this like you can with other dialog boxes using “Hidden Message Settings”. “Security Options” does not help either.
The trusted files are saved in Windows Registry so there’s a way to solve this. As always when editing the Registry be careful and backup if needed.
USERTAPS below HKEY_CURRENT_USER\Software\Autodesk\AutoCAD\R21.0\ACAD-0001:409\AutodeskApps holds apps that have been manually approved. R21.0\ACAD-0001:409 (this is for AutoCAD 2017) is depending on AutoCAD version and if it’s a vertical like AutoCAD Architecture or so.
If USERTAPS is deleted AutoCAD will show the dialog box “Security - Unsigned Executable File” again for all unsigned files.
Using Visual LISP you can delete USERTAPS like this: