Se connecter a l'interface d'administration de votre VM, puis cliquer sur le bouton USB CONTROLER:

Puis sélectionner le contrôleur de périphérique de stockage de masse:

Du coté du système hébergé dans la VM vous devriez voir apparaitre le périphérique USB au niveau du système:

debSrv:/# dmesg [ 3227.555607] usb-storage: device found at 5
[ 3227.555608] usb-storage: waiting for device to settle before scanning
[ 3232.595382] usb-storage: device scan complete
[ 3232.599622] scsi 1:0:0:0: Direct-Access              USB Flash Memory PMAP PQ: 0 ANSI: 0 CCS
[ 3232.616057] sd 1:0:0:0: [sda] 7870464 512-byte hardware sectors (4030 MB)
[ 3232.625592] sd 1:0:0:0: [sda] Write Protect is off
[ 3232.625595] sd 1:0:0:0: [sda] Mode Sense: 23 00 00 00
[ 3232.625597] sd 1:0:0:0: [sda] Assuming drive cache: write through
[ 3232.649238] sd 1:0:0:0: [sda] 7870464 512-byte hardware sectors (4030 MB)
[ 3232.651911] sd 1:0:0:0: [sda] Write Protect is off
[ 3232.651915] sd 1:0:0:0: [sda] Mode Sense: 23 00 00 00
[ 3232.651918] sd 1:0:0:0: [sda] Assuming drive cache: write through
[ 3232.652226]  sda: sda1
[ 3232.655673] sd 1:0:0:0: [sda] Attached SCSI removable disk