Samsung Galaxy S3
Galaxy S3 users, who have updated their 
devices to Android 4.3 and wish to root the 
same, may follow our step-by-step guide.
The tutorial uses CF-Auto-Root file 
released by recognised XDA developer, 
Chainfire. The CF-Auto-Root is firmware
 independent, it completely supports 
Android 4.3Jelly Bean and future firmwares as
 well. 
Pre-requisites
1) Install USB Driver for Samsung Galaxy S3 
to transfer files between the Android device
 and the computer.
2) Enable USB Debugging Mode on phone to connect it with computer and use Android SDK
 with it. [Press Menu>> Settings>> Applications. From there navigate 
and click on Development option and check USB Debugging Mode.]  
3) As the tutorial might wipe out all data of the phone, create a backup. If the device is having any
 custom recoveries such as ClockworkMod/TWRP already installed, backup data using the 
recovery.
4) If the Android phone powers off due to lack of battery while the installation process, it could
 damage the device. Therefore, the Galaxy S3 should have charge above 80% battery charge.  
5) The phone should be factory unlocked and not locked to any particular carrier.
6) The device will lose manufacturer's warranty once it is rooted. However, users can reclaim the
 warranty back by unrooting the handset later.
7) The CF-Auto-Root files work only on Samsung Galaxy S3 GT-I9300. As applying these
 on any incorrect variant might brick the device, verify the model number of Galaxy S3 by
 navigating toSettings>> About phone>> Model number.  
Steps to root Samsung Galaxy S3 GT-I9300 on Android 4.3 Jelly Bean
Step-1: Download CF-Auto-Root file for Galaxy S3 to computer
Step-2: Extract the downloaded root zip using Winzip, 7zip, winrar or any other extracting tool
 to getCF-Auto-Root-m0-m0xx-gti9300.tar.md5 file      
Step-3: Download Odin3_v3.07. Extract the Odin zip to get Odin3 v3.07.exe file
Step-4: Switch off Galaxy S3
Step-5: Enter into Download Mode by pressing and holding 
Volume Down, Home and Power buttons together until the construction Android robot icon
 with a warning triangle appears on the phone's screen. Then press the Volume Up button to
 enter into Download Mode
Step-6: Run Odin3 v3.07.exe as Administrator   
Step-7: Connect the phone to the computer using USB cable while it is in Download Mode. 
Wait for some time until Odin detects the device. When the phone is connected 
successfully, anAdded message will appear under Odin message box. Additionally, the ID: 
COM box in Odin will turn blue with the COM port number indicating successful connection  
Note: If the Added message does not appear, try another USB port, try the one located at the 
back side of the computer. In case Odin still fails to recognise the device then reinstall USB driver. 

Step-8: In Odin, click the PDA button and select CF-Auto-Root-m0-m0xx-gti9300.tar.md5 
which was extracted earlier    
Step-9: Ensure Auto-Reboot and F.Reset Time checkboxes are selected in Odin
Step-10: Click the Start button in Odin. The installation process should begin now and take few
 minutes to complete
Step-11: After the installation process is completed, the phone will restart and soon a PASS
message with green background will  appear in the extreme left box at the very top of Odin. 
Once the home screen appears, unplug the USB cable from the phone to disconnect it from 
computer
Galaxy S3 running on Android 4.3 Jelly Bean firmware should now be rooted 
successfully. You mayinstall any app that requires root permission. Also, verify the root 
status of the device by downloading Root Checker app from Google Play Store.  
Troubleshoot issues
Sometimes the device does not boot into Recovery Mode and root the device. In that case, 
perform the entire procedure again. If it still does not install root, ensure Auto Reboot checkbox
 in Odin is not checked. Then after flashing the root package, pull out the battery and boot the
 phone into Recovery mode by selecting Volume Up, Home and Power buttons together.
 This will start the install process.