Thanks to the XDA forum developer Chainfire now he introduce easier method. This method we first install unofficial CWM using PC ODIN and then root the device by flashing SuperSU , SU binary, busybox.
- ClockWorkMod (CWM) Recovery in here
- PC ODIN in here
- Clockworkmod manager in here
- CWM superSU in here
- If your not install Samsung Kies get it in here.
- Use volume keys for navigation
- Use home button for selection.
- Unzip downloaded ODIN file, now you will receive “Odin3 v1.85.exe” and “Odin3.ini”
- Unzip downloaded “CF-SGS3-CWM-v5.5-v1.2″ now you will receive “CF-SGS3-CWM-v5.5-v1.2.tar” don’t extract “.tar” file.
- Move downloaded SuperSU into your phone’s SD card
- Disconnect your Galaxy S3 from your computer.
- Run the ODIN application by double click on its “Odin3 v1.85.exe” file
- Connect your phone to the PC via USB cable.
- Power off your phone
- Enable download mode by press and hold “Volume down, Home and Power” buttons together.
- If ODIN application displays “Sucessful” under the message and first ID:COM” highlighted yellow color, your phone successfully detected. If not install the Samsung Kies.
- Now check Repartition is NOT ticked and auto reboot ticked, other options leave as it is.
- Click “PAD” button under the odin’s “Files [Download]” and select “CF-SGS3-CWM-v5.5-v1.2.tar” file.
- To flash CWM click “Start” button
- Wait for a few seconds to complete the installation.
- Now your phone will be rebooted.
- First follow above clockworkmod flashing step.
- Now shut down your phone.
- Boot into recovery mode by pres and hold volume up, home and power buttons together few seconds.
- Now on the CWM go to “install zip from sdcard> Choose zip from the SD card”
- Now select the CWM-SuperSU file that you moved to the SD card
- Select “Yes-Install…..”
- Go back and select “Reboot system”
- Now you rooted your Samsung Galaxy S III I9300 ( S 3 )
[via XDA forum].