I've just done a direct download of 4.0.8 onto my 4.0.7 and Norton reported it as safe.
If WD is only reporting this Trojan when running the program from an USB stick then I would suggest that you download the free version of MBAM and scan that drive.
https://www.malwarebytes.com/mwb-download/Click on Scan in the left pane then on Custom Scan/Configure Scan and check the box for the USB drive and see what it reports.
For the program itself, that is a false positive.
However, my Norton Security went through a phase of kicking out the program's .exe and I had to white list it for a while until the Definitions moved on.