I9500_4.4.2_I9500XXUFNB4_Kitkat_Root & disable knox security here
Imp note : this root guide only for 9500XXUFNB4 running 4.4.2 firmware only...!!
downlod required file :
Run the Odin3 v3.09.exe file as an administrator
Now connect your Galaxy S4 I9500 to your computer via USB cable (downlod mode )
Make sure that, only the “Auto Reboot” and “F. Reset Time” options are checked.
Now, click on the AP (PDA in older Odin) button and select the CF-Auto-Root-ja3g-ja3gxx-gti9500.tar.md5 file.
Finally, click on the Start button to begin the rooting process, wait few moments.