The U.S. Snapdragon Samsung Galaxy devices have little hope in the way of custom development because the carriers mandate that Samsung not release an official bootloader unlock tool. The only way for these devices to get root access is for an exploit to be found. For the Samsung Galaxy S8, Samsung Galaxy S8+, and Samsung Galaxy Note 8, that’s exactly what happened with the SamFail exploit. Taking advantage of root access, XDA Senior Member afaneh92 has created a Safestrap recovery for the three devices. Safestrap recovery is just like TWRP, but it works with a locked bootloader.
Safestrap is a recovery for phones with a locked bootloader. It is based on TWRP 3.2.1 and works using root which is currently available with the SamFail exploit. It works by showing you a splash screen when you reboot your phone that allows you to boot to Safestrap recovery or to the system. The recovery allows you to have up to 4 ROM slots alongside the stock ROM.
When flashing a file, you can select the ROM slot you want to flash to and then you can go back and flash a file, make a backup, restore a backup, or erase partitions just like normal TWRP for phones with an unlocked bootloader. Along with all the features in normal TWRP, the developer has added a boot options menu that allows you to create virtual ROM slots. These are stored in the data partition so the more ROMs you have, the less usable storage you will have.
If you do install Safestrap on the Samsung Galaxy S8, Galaxy S8+, or Galaxy Note 8 be aware it will be limited to just Android Nougat. This will also limit you to 80% because of the root method used. This is sadly because the only known way to get root access on the Galaxy S8, S8+, and Note 8 is via the SamFail exploit which has since been patched. Currently, you might not be able to install fully custom AOSP-based ROMs such as LineageOS 14.1, but it could be possible soon.
How to install Safestrap Recovery on the Samsung Galaxy S8/S8+ and Samsung Galaxy Note 8
To flash Safestrap recovery, you need to root your phone using one of the above root methods for the Galaxy S8, S8+, or Note 8. After rooting your phone you need to go to the Google Play Store and install a busybox installer and then install busybox.
Once that is installed, you will have to install the Safestrap APK on your device.
In the Safestrap app, you have to agree to the terms and then select the “install recovery” button. You will know it’s installed when the status shown in the app changes to “installed”. Once installed, you can reboot your phone and you should see the splash screen. Finally, to access Safestrap recovery, you select the menu button on the splash screen. Once you get to the menu, you will have access to Safestrap.