I think the "no effective defense" slide (#20) is kind of disappointing. Their whole talk, for me, circles around the "someone plugs in a USB device with surprising functionality" narrative... And there are two possible things that can go on. First, the device could try to exploit flaws in parsing of USB descriptors. This is how the PS2, I think, was sucessfully rooted/unlocked/made-linux-run-on-it.

But the talk linked to mainly focuses on the second possibility: "the OS automatically loads the driver for keyboards and network adapterse", and this is trivially defended against, at least on Linux. I assume you can do similar/identical things on other operating systems (e.g. Windows probably has a registry key for that, because it always has registry keys for everything...)

# echo 0 >/sys/bus/usb/drivers_autoprobe

Now, no drivers are bound to USB devices automatically. Just try it. I plugged in peripherals into the computer, the only thing you'll get (running 3.15.8-1-ARCH, archlinux x64) is the following text in the dmesg:

[ 6765.949361] usb 5-1: new low-speed USB device number 3 using uhci_hcd **mouse**
[ 6846.469357] usb 6-1: new high-speed USB device number 3 using ehci-pci **harddisk**
[ 7062.616021] usb 7-4.4: new high-speed USB device number 7 using ehci-pci **eth/network**

Now, if I am convinced that one of the devices hasn't been tampered with, I'll run the following command, that triggers automatic probing for a single USB device (1.0 is configuration 1, function 0, I think...)

# echo 7-4.4:1.0 >/sys/bus/usb/drivers_probe

dmesg shows....

[ 7193.076584] ax88179_178a 7-4.4:1.0 eth0: register 'ax88179_178a' at usb-0000:00:1d.7-4.4, ASIX AX88179 USB 3.0 Gigabit Ethernet, 00:0a:cd:22:b4:40
[ 7193.099754] systemd-udevd[10470]: renamed network interface eth0 to enp0s29f7u4u4

But if I only want to allow USB storage devices, I can manually bind to the usb storage driver.

# modprobe usb-storage # was not loaded on my machine, yet...
# echo 1 >/sys/bus/usb/devices/6-1/bConfigurationValue # enable 1st configuration
# echo 6-1:1.0 >/sys/bus/usb/drivers/usb-storage/bind

dmesg, again...

[ 7583.801824] usbcore: registered new interface driver usb-storage
[ 7729.898188] usb-storage 6-1:1.0: USB Mass Storage device detected
[ 7729.898404] scsi6 : usb-storage 6-1:1.0
[ 7730.900552] scsi 6:0:0:0: Direct-Access TOSHIBA MK4309MAT G5.0 PQ: 0 ANSI: 0 CCS
[ 7730.904913] sd 6:0:0:0: [sdd] 8452080 512-byte logical blocks: (4.32 GB/4.02 GiB)

Now, this of course is completely ridiculous, from a user-interface perspective, but, I think if you only want to cover mounting of USB sticks, you can script this in shell/perl/python/awk, using "lsusb -v" for parsing the binary USB descriptors and only start usb-storage on USB sticks.

EDIT/ADDED: -----

And also note: The mechanism described above concerns the binding of drivers to devices. There's a different facility in place to make USB devices inaccessible to the drivers/the user, and that's using the "authorized" flags: You set the "autorized_default" flag in /sys/bus/usb/devices/usb<N> to 0, then every device that is connected to the machine is initially disabled:

[ 9162.809251] usb 7-4.4: new high-speed USB device number 11 using ehci-pci
[ 9162.912337] usb 7-4.4: Device is not authorized for usage

If you are sure that this particular device is allowed to connect, authorize it...

# echo 1 >/sys/bus/usb/devices/7-4.4/authorized

[ 9214.302656] ax88179_178a 7-4.4:1.0 eth0: register 'ax88179_178a' at usb-0000:00:1d.7-4.4, ASIX AX88179 USB 3.0 Gigabit Ethernet, 00:0a:cd:22:b4:40
[ 9214.302678] usb 7-4.4: authorized to connect
[ 9214.326028] systemd-udevd[10771]: renamed network interface eth0 to enp0s29f7u4u4

That way, you could have the publicly accessible USB connectors (say... usb2 and usb4) in "autorized_default=0" mode, and the internal USB connectors, or the ones on the back of a device that is somewhat physically secured set to "autorized_default=1" to not impede usage and comfort... But, of course, if you have scripts in place implementing a "USB ACL", that doesn't really sound as if it's worth the added complexity?