However I was able to get USB support for USB hard drives using Virtual box 3.2.8 and Linux Mint but many reboots are needed both host and guest. Also the USB is not shared, you must add and remove from host and guest VM.
Also needed on the host you add a virtual USB device and just take the defaults to load the drivers. Once you install virtual box, you must add the usb devices in the vm setting, nice interface here, then add the devices from the status bar as show here.
Note USB Drive appeared on desktop since it was automounted from Linux Mint.