virtualbox.org

Host: Windows 7 Home Premium (64 bit)
Guest: Windows 7 Professional (32 bit)

When I pluck in a thumbdrive, the VM can install the driver and detect the thumbdrive, but the guest always fails to install the driver for the thumbdrive even though internet is connected ok. When I check the device manager, it says that the drivers for the base system device are not installed. When I try to update the driver, it says "Windows could not find driver software for your device".

From the device instance path (PCI\VEN_80EE&DEV_CAFE&SUBSYS_00000000&REV_00\3&267A616&0&20), I figured out that the vendor and device ID is 80EE:CAFE, and when I googled it I found that is called the VirtualBox Guest Service.

May I know where I can download this driver? Thank you.

VirtualBox does not install any USB drivers inside the guest. It does however install USB filter drivers on the host, which redirect packets from the filtered USB device to the VM and back. The appropriate redirection drivers are included with VirtualBox, there is no need for you to search for them: simply allow the default drivers to be installed.

Typically you add a filter matching the device to your VM settings. You then boot up the VM, wait for it to finish then plug in the device. You allow the filter driver to be installed on the host (a "New hardware found" alert will have popped up), then you unplug and re-plug the USB device. At this point the guest should detect the device and prompt for any guest drivers it requires, if any are needed. Since I don't do support for the device I will be unable to comment on why it can't find drivers on the internet, should that problem continue.

try to install Guest Additions

The guest additions have nothing to do with this. USB is handled as virtual hardware, not a guest program. E.g. you can use USB with a Win98 guest, for which no GAs are available.