Windows 8 Certificate Warning: We can't verify who created this file

Question

Despite successfully signing my C++ app on Windows 8 with signtool with a valid timestamp server and certificate, when I (local) or my users (remote) attempt to run the app, Windows displays the following message:

Open File - Security Warning We can't verify who created this file. Are you sure you want to run this file?

I am using signtool with a Comodo certificate and sign with options /f, /p, and /tr. I am confident that the signature is successful because it removes most of the runtime security warnings for my users.

'Security Warning' Dialog:

Answer 1

It seems that Microsoft, in 2013, made a change to Windows such that executables opened from a network drive will ALWAYS give this warning, even if they are signed. Source (it is brought up in the comments section by Kraig Whiting): Everything you need to know about Authenticode Code Signing - IEInternals - MSDN Blogs (archive link)

It seems the only way to make this go away is to do what user4437298 suggested, which is to add the network drive as a trusted zone.

Answer 2

Add your z:\ drive to trusted sites in internet explorer local intranet advanced options