The Samsung Galaxy S3 is turning into a secondary smartphone for many since it’s aging rapidly. Today the Samsung Galaxy S5 is out and that makes the S3 far more expendable. As you probably know, applying root access is taking away the default factory restrictions in place by the manufacturer. That’s why when we following steps like this the warranty is immediately void. The only way to have the warranty working again is to unroot the same. That said, most of you won’t have any warranty remaining since the mobile is several years old now.

If you are on your S3 then you will open up the operating system to tons of new possibilities including custom ROMs, custom recoveries, custom firmware and extra applications from the Google Play store that you couldn’t use without the internals unlocked.


The tool we are using today is the CASUAL rooting tool that works from the scripts as the CF-Auto-Root by our beloved Chainfire. We consistently use Chainfire’s work here on site because we love the close to stock Android experience and it’s easy. Correspondingly, this method is quick and easy too. The developer of casual is Adam Outler — the same man who unlocked the bootloader of the Note 2 for Verizon subscribers.

Casual works with Windows, Mac and Linux computers, notebooks or laptops that have the USB slot on the side. Adam says that the Mac version is still in ‘experiential’ stages so you may want to use one of the other options instead. We must have the slot because we are connecting our handsets to the computer. Files are often downloaded to the computer before being transferred over to the mobile device because it’s safer.

What Is Rooting the Android Operating System?

When you buy a new smartphone, you might not know it, but the Android operating system is in a “locked” state. For the most part, it will not make much difference to you: most apps are still available to use, and there are benefits to this locked state such as better security. When you root the Android operating system, you are gaining full administrative rights over the OS.

Why Would You Want to Root Android?

Gaining full administrative rights over the operating system has some perks to some people. For example, out of the millions of applications available on Google Play, some of them will not be able to run on your device unless it has root access. Until you have a specific need for wanting Android rooted, you probably want to leave Android as it comes out of the box. But if you need to unlock an app, then that is when you want to look into rooting methods. Using more apps is only one example of why you may want root access, here is the full list of benefits:

  • Unlock more applications. Some of the apps available for Android cannot run unless you have root access. This is because the app’s features cannot run without the root permissions because the features require the full system access before they can be useful.
  • Better battery life. Smartphones are great, but they have one caveat, which is each time you recharge the battery, it loses some of its overall lifespan. That means smartphones, in general, do not make great investments, and if your weekly paycheck is low, you will want to limit the number of smartphones you go through. One of the ways you can do that is by removing bloatware and creating a better battery life.
  • Bolster performance. If you are the budget-conscious shopper, you may want to increase the device’s performance. This can be done by removing the bloatware as well. The more processes you have running, the more memory that is used. By removing some of the apps, it can help lighten the load on your hardware.
  • Customize Android with themes. With root access, you can download and install any theme that’s at your disposal. That includes any customized theme you can find.

What Are the Risks of Rooting?

If you are buying a smartphone that is not running iOS, then it is probably the Android operating system that you want running as the ideal software to pair with your shiny new hardware. It is, in fact, the Android OS that offers you the chance to customize the OS considerably more than iOS: custom themes, run any app you know about, the works. For many users, the “openness” of an operating system is important, because it offers them more freedom which means running into fewer problems with their investments. But there is a reason iOS likes a far more locked approach: the ability to customize is not for everyone, and if you do not know what you are doing it can lead to a lot of problems which can define your time with the OS rather than freedom.

With power (full admin permissions) comes greater responsibility. Here are some of the main risk factors when it comes to rooting:

  • Malware becomes a larger threat. You might read the occasional news article about how new malware is wreaking havoc in parts of the world on Android. But the Android operating system with root access becomes considerably more vulnerable to exploits because applications are no longer prisoned off in their own sandbox environments. This means if you accidentally download malware, it can do more damage because it can spread throughout the operating system and even jump into other applications and potentially view sensitive data.
  • You can accidentally brick the smartphone. There is always a chance that you end up bricking the smartphone before you had the opportunity to use it with root access. That is because if you are going to brick it, it is going to happen during the rooting process.
  • You may void the warranty. Most manufacturers do not allow you to root the Android operating system and still get to bring it in for repairs under warranty. Whether they are legally meant to do that or not is another question, but it is now common knowledge that most do not want to help you if they find out you have unlocked the OS with root access.

Details of Note

  • Use this tool only for the SGH-i747 model of the Samsung galaxy S3 smartphone. You can anytime check your phone’s version in the ‘About Device’ menu.
  • Do not try attempt to flash the file in this post on any other Android device. It doesn’t work and it can cause soft-bricking.
  • Download and install the latest Samsung USB Drivers on your computer. You can find them from third-party links, the official Sammy website or with Kies. Similarly, you may wish to install Samsung kies and install the drivers that way.
  • You must backup the device if you lose data. Backup the phone contacts, call logs, MMS texts, SMS messages, videos, pictures, music and all other data. Download Helium from the Play Store if you don’t know any apps for making copies of the data. Helium syncs the contacts, backs up the messages and market apps. Moreover, you should make a copy of the EFS folder for when it is corrupt.
  • Disable Kies before you start the guide below and after you get the drivers.
  • Temporarily disable all antivirus from the Android and the computer. It comes from apps on Mobile and you can visit the system tray to disable security from Windows.
  • Do not go past this point unless you are an advanced Android user.
  • Check the battery charge level from the status bar. It wants to have at least 60% battery power before starting. The guides short, but the device is old and that’s why we want to save up some extra power. Some of you will have USB charging working so the battery charges when it’s plugged into the computer.
  • This method is not tested on the Windows 8 OS or the Raspberry PI. You are safer using Windows 7, OS X mountain Lion, OS X Lion, Debian Linux 64 and 32 bit.
  • You must be running the latest version of “java” on the computer. Check the system tray for any java updates. If there aren’t any ready for installing you are likely running the latest version. If you don’t see java you must download the file from the official website.
  • After completing the guide the KNOX flags will be triggered and it loses the warranty. If you are satisfied with all that it’s time to start the steps.

How to root the AT&T Samsung Galaxy S3 SGH-i747 using the CASUAL package

  1. Turn the computer on and log in to the user account of your choice.
  2. Download the casual file from this page to the desktop of the computer.
  3. Double click the jar file on the desktop and launch the program.
  4. Find the USB cable for the mobile.
  5. Boot the S3 in Download mode
    – press Volume Down + Power + Home keys at the same time.
  6. Connect the S3 to the computer using the USB wire.
  7. Look at the bottom of the screen for a message saying “device connected.”
  8. Press the “do it!” button just above where it says device connected.
  9. Wait for the flashing to finish.
  10. Do not touch any buttons until it finishes.
  11. Disconnect the mobile from the computer safely by stopping the USB mass Storage device.

If you get stuck in a boot loop you must enter the recovery mode. From there select ‘wipe data/ factory reset.’ Download the Root Checker Pro application from Google Play to check it’s working.