Root Galaxy S3 On Android 4.1.2 [How-To Tutorial]

Step 1: Download both Odin3 and CF-Auto Root packages from the link above. Extract the contents of the root package to a location of your choice.
Step 2: Launch Odin3, click the PDA button and select the .tar.md5 file that you extracted from the CF Root package.
Step 3: Make sure that Re-partition is unchecked in Odin3, and that nothing is selected in PIT.
Step 4: Turn off your Galaxy S III and put it in download mode by pressing and holding volume down+power+home at the same time, and then pressing volume up for confirmation.
Step 5: With your device in Download Mode, connect it to the PC using the USB cable. If all went correct, Odin3 will detect the device, indicated by a COM address in the top left corner of Odin3.
Step 6: Double check that the correct PDA file is selected and that re-partition isn’t checked, and hit the Start button to begin flashing the rooted kernel.
Step 7: Once the flash is complete, the phone will reboot and enter recovery mode, automatically initiating the rooting procedure. It will reboot once more.