VirtualBox can boot virtual machines from USB flash drives, allowing you to boot a live Linux system or install an operating system from a bootable USB device. This option is well-hidden. Source : http://www.howtogeek.com/187721/how-to-boot-from-a-usb-drive-in-virtualbox/
SCCM Clients that simply cannot get installed and they get this specific failure in the ccmsetup.log:
Task Sequence Wizard returns with message that it can't find a Task Sequence for the machine.