How To: Root Your AT&T Samsung Galaxy S4 (MF3 Firmware)

Root Your AT&T Samsung Galaxy S4 (MF3 Firmware)

Rooting is usually the first thing on the to-do list whenever one of us softModders gets a new Android device. Unfortunately our efforts are sometimes hindered by certain obstacles; a common one is a locked bootloader.

What Is a Bootloader?

A bootloader is the lowest level software on your Android device, starting up your phone when you press the power button, initializing everything, then handing control over to the Android operating system. Carriers often lock the bootloaders on their phones, and AT&T has done so with their Samsung Galaxy S4s and thrown away the key.

When the AT&T GS4 was first released, developers had found a way around the bootloader. AT&T then pushed out a firmware update (known as MF3), which patched up the exploit.

While our bootloader is locked, we can still have root thanks to the work of XDA's jortex. You can check out his original thread here.

What You Should Know Before Starting

  • This guide is only for AT&T Galaxy S4s with MF3 firmware (see the next section to double-check if you can use this guide).
  • At this time, there are no custom recoveries compatible with GS4s on MF3 firmware. A recovery is a software for your phone that allows you to flash custom ROMs like CyanogenMod, so without one, you won't be able to install ROMs on your phone.

Video Walkthrough

Before You Proceed

Remember, this guide is only meant for the AT&T Galaxy S4 with MF3 firmware. To find out your firmware, go to your phone's Settings -> More -> About device, then check Baseband version.

If the last three characters of its number are MF3 (for example, I337UCUAMF3), then you can proceed with this rooting guide.

What You'll Need

For this guide you will need:

  • A microSD card
  • SD card reader
  • Root_for_ATTSG4_FM3.rar file from jortex's XDA thread.
  • A desktop computer. I'll be doing this tutorial with Windows 7, but the steps should be manageable with Mac and Linux as well.

Step 1: Unmount & Remove Your GS4's microSD Card

You'll have to connect your microSD card to your PC via a card reader in the next step (connecting through your phone will not work). Before you remove your microSD card, don't forget to properly unmount it to prevent any data loss.

If you don't know how to do that, go to your GS4's Settings -> More -> Storage, select Unmount SD card, then tap OK at the confirmation window.

Step 2: Format Your microSD Card to exFAT

This step will delete everything from your SD card, so make a backup of everything on there. Create a folder in your Documents, name it SD Card Backup, then copy and paste all your SD card's contents.

Once you've backed up everything, right-click on the drive containing your SD card and select Format. The following window should pop up:

Under File system make sure exFAT is selected, and under Format options make sure Quick Format is unchecked. Click the Start button, then OK on the confirmation window.

Depending on factors like how big your SD card is, or how fast your PC or card reader are, this step may take some time.

Step 3: Unzip the .Rar File onto Your SD Card

If you don't have any unzipping software on your computer, I recommend this free one called 7-Zip.

Make sure you unzip to the root level of the card (e.g. not in a folder). You'll see the following files:

  • A folder titled gs4ex
  • pwn

Step 4: Reinsert the Card Back into Your GS4

After reinserting, head to your GS4's Settings -> More -> Storage and make sure you can see your SD card.

Step 5: Install Android Terminal Emulator

Download and install Android Terminal Emulator by Jack Palevich, available on the Google Play Store for free.

We'll be using this app to input a few commands in the next step, so open it up once you have it installed.

Step 6: Input the Following Commands

It is very important that you input these commands exactly as shown—they are case sensitive. Enter them one at a time, in order.

  1. cd /mnt/extSdCard
  2. ./pwn
  3. ./

It should look something like this after everything's been entered:

Step 7: Check if SuperSU Was Installed

That last command that we ran through Android Terminal Emulator, ./, is supposed to install an app called SuperSU.

Developed by chainfire, SuperSU helps you manage root permissions, by displaying a Grant or Deny prompt every time an app attempts to access root.

The script is supposed to install it, but some GS4 owners using this root method have had trouble. Check your app drawer, and if it's not there, you can simply download and install it from the Google Play Store.

Step 8: Verify Root with Root Checker

Download joeykrim's very popular Root Checker, which verifies whether your device has root or not.

Open up the app then tap on the Verify Root Access button. A Superuser request should pop up, so select Grant.

You should now see the words that every softModder yearns to see on their phone:

Step 9: Reboot & Run Root Checker Again

We're not quite done yet, we just have one quick thing to do. Simply restart your phone, then run Root Checker a second time to make sure you still have root after rebooting.

If you run into any issues, feel free to ask questions in the discussion section below.

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This was the best put together video I have ever watched and used. VERY Thorough!!!!! Using the photo inserts the locations and links to apps and the video not rushed or vague. Way KUDOS.......WAY!

Phone rooted after doing day,phone unroot itself.

So am I correct in my thinking here. If I have this MF3 update on my rooted s4, I cannot install cyanogenmod at this time?

Correct. We need to wait for a custom recovery.

thank you for the response

I did this and everything went great. Unfortunately I dl rom toolbox and changed some things and my phone is now messed up. Is there anyway to flash the stock firmware back ?

What sort of changes did you make? When you say the phone is 'messed up', how so? Does it boot up?

At the moment there's no stock firmware image to flash.

I have bricked one S4 doing this. I have received another S4 just wondering if anyone else has had issues with bricking or if it was just me?

Will doing this erase my phone contents?

No, anything on your GS4's internal storage will be untouched. If you have important items on your external SD card, make sure to back them up in Step 2.

so if we dont have custom recovery yet what will happen to phone if we root. will it quit working if i reboot?

The phone should be fine after rebooting.

Without a custom recovery, you won't be able to flash any ROMs like CyanogenMod. However, with root, you can customize your stock TouchWiz ROM with the Xposed framework.

ok thanks so if i dont do anything but root and maybe trick phone into a hotspot i should be fine. im new to roms so i wont be adding any soon,.

i didnt think that odin would work on the OTA mf3 s4? i just want to root to trick phone into hotspot. do i need custom recovery for that.

Just a note: you don't need to do all the cumbersome steps of taking the SD card out and popping it into another machine, putting the stuff on it and popping it back into the phone.

Just follow these simple steps:

  1. format the SD card in the phone itself (Settings -> More... -> Storage -> Format SD Card). ONLY DO THIS IF YOU HAVE NOT ALREADY FORMATTED IT OR YOU WILL ERASE EVERYTHING ON THE CARD
  2. Install Rar Extractor from the play store,
  3. then tap the Root_for_ATTSG4_FM3.rar link.
  4. Pull down your notifications screen and wait for it to finish downloading.
  5. Once it is done, tap it, and Rar Extractor will open up. Choose the directory /mnt/extSdCard to extract it, and then follow the rest of the steps.

It works beautifully!

Double check that all three files are on your SD card, also make sure your card is formatted to exFAT.

After doing this is a way to unroot and/or put back to stock without avoiding the warranty?

As far as I know, there are no official ways to unroot. I know two methods that can get you unroote though:

  1. I read about a flashable Odin MF3 firmware on XDA and someone has also gotten ahold of the Samsung SMART application from Best Buy
  2. Chainfire's "SuperSU" app on the Play Store has an Unroot option that removes the su binaries from the device

when i try to introduce the command ./pwn, it displays the message: "/system/bin/sh: ./pwn: can't execute: Permission denied"

Yeah, if you're on 4.3, you'd be on MK2, not MF3, which this guide is for.

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