We're developing a site that will only run on the intranet, and computers with access to this intranet will have this executable installed.
Does this mean the EXE is already installed on the desktop? You just want to launch it from the website?
If so, you can associate the EXE with a MIME Content Type and when the user clicks it, it will launch.
Pick a Content Type and a file extension, for your EXE name, for instance:
CauseChaos.exe
Associated with .chaos file extenstion
Content Type will be: application/chaos
Associate the file extension with your EXE via the EXE install. I show it here, using InnoSetup
[Registry]
Root: HKCR; Subkey: .chaos; ValueType: string; ValueData: CauseChaos; Flags: uninsdeletekey
Root: HKCR; Subkey: CauseChaos; ValueType: string; ValueData: CauseChaos Tool; Flags: uninsdeletekey
Root: HKCR; Subkey: CauseChaos\DefaultIcon; ValueType: string; ValueData: {app}\CauseChaos.exe,0; Flags: uninsdeletekey
Root: HKCR; Subkey: CauseChaos\shell\open\command; ValueType: string; ValueData: "{app}\CauseChaos.exe ""%1"""; Flags: uninsdeletekey
Associate the MIME content type with the file extension, through the EXE install.
[Registry] (continued...)
Root: HKCR; Subkey: HKCR\Mime\Database\Content Type\application/chaos; ValueType: string; ValueName: Extension; ValueData: .chaos; Flags: uninsdeletevalue