For this software, so for them there is a free and reliable solution to block or disable USB storage devices on mac by removing or unloading the built-in USB storage device driver extension in OS X. Use the following instructions. USB Block is an improved USB Blocking software that restricts all the drives, disk, and ports that are unauthorized. Above all, USB Block lets you block devices even in safe mode, making it impossible for the third party to copy your personal files and documents from the boot menu.