Currently I am running Arch Linux, but to see if this applies to you just check if a file exists at the following location: '/sys/class/leds/samsung::kbd_backlight/brightness'.
If there is indeed a file at this location, you should be able to (with the correct privileges) be able to store values in that file between 0 and 8 that will correspondingly set the keyboard brightness.
I currently have a few scripts to do this work for me which are embedded below. (or at )
The first two scripts are stored on my computer somewhere in the default $PATH (e.g. /usr/bin worked for me). The last is a script to set the mode of the brightness file. This has to be run with superuser privileges on boot (to allow the other two scripts permission to access the file).
And there you have it, working keyboard backlight brightness on your Samsung series 9 ultrabook running Linux.