Since VirtualBox version 4.0 USB support can be enabled in the Open Source Edition (OSE) by installing the optional Oracle Extension Pack. You can find out how to install the Extension Pack here. If you have an earlier 3.2 version, you must make sure you have the Oracle closed source version of VirtualBox which was entirely separate from the OSE version.
Once you have everything installed correctly you need to make sure you have the VirtualBox guest additions installed on your guest VM. To do this select Devices -> Install Guest Additions from the VM menu.
Now you should have a USB section in your VirtualBox manager for your guest VM. Power down your guest VM and make sure that the USB and USB 2.0 controller are activated.
When you start your VM you should now see a USB icon on the bottom right corner of the screen. Unfortunately when you click on this the USB devices connected to your host machine are visible but deactivated and therefore invisible to your VM. To fix this we have to add your user to the “vboxusers” group on your host machine.
If your host machine is running a Linux distribution that uses GNOME (Ubuntu/Fedora /etc.) simply go to System -> Administration -> Users and Groups -> Manage Groups and scroll down to the “vboxusers” group. Click on Properties and select the checkbox next to your username to add yourself to th group. Now you must completely logout of your Gnome session and log back in for these changes to take affect.
You should now be able to fire up your VM and have access all USB devices connected to our host machine. Click the USB icon to see what USB devices are available. You will know if the USB device is visible to your VM if there is a check mark next to it.