These are the instructions to root Samsung Galaxy S2 SGH-I777 AT&T Smartphone (running on android 2.3.4) using iRoot Application on Windows Computer.
Requirements: Your Samsung Galaxy S2 SGH-I777 AT&T Smartphone should have 20-30 percent of phone battery to perform the rooting process.
(Developers Option is hidden for Android 4.2.2 or above, to unhide Go to Settings > About Phone > Built Number (Tap on it for 5-8 times).
Congratulations! Your Samsung SGH-I777 Device is now Rooted. You can also verify the root status of your device by using the Root Checker App.
[*] No data loss process: Your Samsung Galaxy S2 SGH-I777 AT&T Phone Data like contacts, pictures, videos, music and etc will be not affected with the above method.
[*] Warranty Void: Your Samsung Galaxy S2 SGH-I777 AT&T Warranty may be Void after following the above tutorial.
[*] iRoot Android App: You can also root your Android Device through the official iRoot Android App. If you wish, you can download the iRoot Android App from here.
[*] Samsung Stock Firmware: If you are looking for the original firmware for your device, then head over to Download Samsung Stock Firmware page.
[*] Samsung USB Driver: If you are looking for the original USB Driver for your device, then head over to Download Samsung USB Driver page.
[*] Credits: iRoot is created and distributed by Shenzhen (Developer), so full credit goes to them for sharing the Application for free.