There has been a discussion on reboot.pro recently about how to write-protect a USB drive.
It is not advisable to hardware write-protect an E2B USB drive because E2B needs write-access to the MBR (to modify it) as well as needing to modify other files (e.g. \autounattend.xml, etc.). Some WinPE's and linux's (via ISOBOOT) may be able to boot from a write-protected E2B drive though. I intend to investigate this further at a later date, to see just what is possible if the whole E2B USB drive is hardware write-protected.
So the use of the write-protect switch on the Netac USB 3.0 U335 flash drive, for instance, is not a recommended option when booting from an E2B drive (although once it has booted to an OS from the flash drive, you could remove the USB drive - flip on the WP switch - and then re-insert it again and hope that it did not have enough time to get infected!).
It is not advisable to hardware write-protect an E2B USB drive because E2B needs write-access to the MBR (to modify it) as well as needing to modify other files (e.g. \autounattend.xml, etc.). Some WinPE's and linux's (via ISOBOOT) may be able to boot from a write-protected E2B drive though. I intend to investigate this further at a later date, to see just what is possible if the whole E2B USB drive is hardware write-protected.
So the use of the write-protect switch on the Netac USB 3.0 U335 flash drive, for instance, is not a recommended option when booting from an E2B drive (although once it has booted to an OS from the flash drive, you could remove the USB drive - flip on the WP switch - and then re-insert it again and hope that it did not have enough time to get infected!).