Lalith Chandra

Rebellion via MDM Prison Break with Odin (Part I)

custom-ROM mdm odin heimdall

This is the first part of my blog where I attempt to flash a new OS into a tablet, that has been carrying a firmware, locked down with heavy restrictions.

For context, I’ve got my hands on a government-provided Samsung tablet (won’t be disclosing model or the provider for paranoia-reasons) which has been “locked” for general usage, and allows only 8 applications that can be used (restricted using a third party MDM software), strictly for academic purposes (including instagram for whatever reasons?).

Now, older versions of these kind of third-party MDM launchers can be disabled by simply:

  • Rebooting into safe mode.
  • Changing default launcher from third party restrictive software to system launcher.

That should work fine… in older tablets (Similar to the Byju’s ones). But the one I have, has even restricted the option to reboot into safe mode. I’ve tried to perform a factory reset, but even the stock recovery menu (which appears holding on vol. up + power button when it’s switched-off) was hidden! Talk about government control!

Now, the most impulsive (and fun) choice would be to flash a whole new ROM (Custom OS) and take over the bootloader, and make the tablet a pet gadget which I’d use however I want. Now, for

Getting Started

I went on to search for different tools to flash firmware into the tablet, and found Odin, a ROM Flashing tool for SAMSUNG Android devices. But it works for windows (ew), so I found a linux alternative, i.e, Heimdall to get the job done.

I went to SamFw obviously, for financial reasons, and got the exact firmware for my device. Remember to keep an eye and NOT to download the whole factory version (that ends with _fac). You need the CHILD files instead. Specifically,

  1. AP_*_user_low_ship_MULTI_CERT_meta*.zip
  2. BL_*_user_low_ship*.zip
  3. CSC_ODM_*_user_low_ship_*.zip

Save these and extract with tar -xvf <filename>. There’ll be multiple images in each tar file, we’ll be mapping them with PIT.

After trying some painful stuff out, I found something depressing about the Tablet. It WAS NOT using Samsung/Odin’s partitions, it was using a MediaTek PIT layout. What this means, is that heimdall CANNOT flash these onto my device(heimdall can work with older exynos based firmware). The depressing part of the problem is that I have to go to windows, and use Odin to do the job.

Now, these are the steps to follow to flash the firmware with odin:

  1. Go into the download mode on tablet, and connect it with your PC. You should see “ Added!!” in it immediately.
  2. Now, load the firmware files into Odin. (You’ll see buttons for each image)
  3. And for a security check, go to options and ensure only Auto Reboot and Reset Time have been checked.
  4. Now click START and wait until Odin displays welcome! with a start button.

Congratulations.

We’ve now flashed new firmware, and CAN use it as a normal Samsung tablet. BUT we’re only halfway done. I’ve been writing this since a week and now I’ve realised the blog may need a third part, but We’ll get to it later.

NOTE!

This is NOT our final goal. We need to install a custom OS in the tablet, which requires OEM Unlock from the device. In most of the devices, the option appears in Developer Options in a week or so. We’ll be doing rest of that after it appears.

Until then, Enjoy your brand new Samsung Tablet(Well, new on atleast the software part).