Hi Neil,
Thank you for reporting it.
I scanned it on VirusTotal and it seems like false positive:
Windows Defender also thinks older versions are a virus threat since its recent virus detection update.
Our Setup.exe is generated with Squirrel and apps built with it sometimes get quarantined as a virus threat which is false positive, like Atom Editor.
I understand it’s frustrating. However, there is not much I can do to prevent this.
I heard that getting a code signing certificate is a way to fix anti virus issues including this Windows Defender issue.
I tried to get a code signing certificate last year but it turned out that it’s not possible at the moment (detail here).
Until Windows Defender fixes its detection algorithm, I’m afraid that this will continue to happen.
You’ll either have to add a policy exclusion for the Setup.exe runs from or whitelist the process itself.
Sorry about that.