Windows 7 32-bit

[bezik46]

Seems to work OK, but it must be 40 characters of the new SN otherwise does not change & does not give any warning (so it looks like it does not work)
Also wmic diskdrive get serialnumber does NOT change! (at least on Win 7 32-bit)
And Windows 10 no longer presents the 40 character hex number by above command, so one can not easily chose WHAT to replace (without text to hex converter)
Good discussion about older Windows bytes swapping is here https://social.technet.microsoft.com/Forums/scriptcenter/en-US/0333dd28-3207-4df8-85c3-7ff540f98464/wmi-disk-serial-number?forum=ITCG&prof=required

[bezik46]

On Windows 10 x64
wmic diskdrive get serialnumber
does NOT change either!
Additionally wmic path win32_physicalmedia get SerialNumber
shows configured value ONLY as running as administrator (elevated). As std user it shows the original value

[Eta76]

Possibly you can modify registry user rights, using RegEdit, maybe the rights of the calling process are used.