Virtualbox HardDisk uuid - what is it in Windows guest?

i thought the hdd uuids in vbox were for the hypervisors use and didn't surface in the client os?

 

They can be read out from the guest OS, Hotbird's License Manager does it.

 

The serial number inside a VirtualBox VM is (by default) derived from the hard disk image uuid, but there are a few additional details.

If you have snapshots, then you have a chain of differencing disk images. The serial number is derived from the very first (parent) hard disk image, not the last image in the chain. You can't easily use "internalcommands sethduuid" on the first image, because the next image in the chain also has a record of the parent's uuid. So "internalcommands sethduuid" is only practical when you have no snapshots.

When using "wmic diskdrive get serialnumber", Windows 8/8.1/10 displays the serial number differently than Windows 7.
For example, if the uuid is set to 12345678-0000-0000-0000-000090abcdef:
In Windows 8+, the serial number is "VB12345678-efcdab90" and is displayed directly as such.
In Windows 7, the serial number is "BV21436587e-cfad9b 0" and it is displayed with each character encoded in hex. The hex encoding is "42 56 32 31 34 33 36 35 38 37 65 2d 63 66 61 64 39 62 20 30", and you see that without the spaces.

There is actually a way to set the serial number more directly in VirtualBox, instead of changing the hard disk image uuid. This method overrides the default serial number derived from the uuid.
To set serial number for a SATA disk:

Code:

VBoxManage setextradata "VM name" "VBoxInternal/Devices/ahci/0/Config/Port0/SerialNumber" "VB12345678-90abcdef"

To set serial number for an IDE disk:

Code:

VBoxManage setextradata "VM name" "VBoxInternal/Devices/piix3ide/0/Config/PrimaryMaster/SerialNumber" "VB12345678-90abcdef"

Note that the extradata settings affect all snapshots of the VM, not just the current one.

Using "wmic diskdrive get serialnumber", in Windows 8+ you get exactly "VB12345678-90abcdef"
In Windows 7 you get "BV214365879-a0cbed f" encoded to hex as "42563231343336353837392d6130636265642066"

P.S.: The above extradata settings, and several more, are documented in the VirtualBox help documentation, in section 9.9.2. under the heading "Configuring the hard disk vendor product data (VPD)"