Any Android user should know that their operating system is full of possibilities, something that differentiates it a lot from iOS, but they should also know that with the possibilities also come complications. Do you know what the folder is EFS? One hint, it has a lot to do with the release of smartphones, as well as the IMEI of the terminals.
Here in Spain we have DNI: National Identity Document. This is made up of the main data of any person, as well as an associated number that identifies each person. Well, in every Android smartphone and in every mobile phone we have an IMEI, a unique number that identifies that phone and is non-transferable. It is a crime in fact to change it, and it can even serve in some cases as a password to certain services. WhatsApp, for example, identifies the correct Android user thanks to the IMEI number. Now, this number can be modified by mistake, and together with this, in the same folder, we find files that if they are deleted can end up with our smartphone permanently.
Does that sound like sudden death to you? Sure it sounds to you. Well, the problem was essentially the deletion of this folder. If by mistake we are the ones who delete this folder, we can say goodbye to the mobile phone, since the only thing that could save it would be the company's technical service.
What's in the EFS folder?
In the EFS folder we find several files:
- nv_data.bak: This is the most important file of all, it contains the information of the IMEI code, the PRODUCTODE, or product code, as well as the SIM UNLOCK. Modifying this file can be used to unlock the smartphone. Android smartphones that come with a factory network lock can be modified so that by modifying the SIM UNLOCK parameter, they can already use SIM cards from another operator. However, this process is anything but safe, so extreme care must be taken when working with the modification of these files and documented well in case some users have already had sudden death problems or the like. Remember that manufacturers are not so stupid to let anyone modify these files in a simple way.
- nv_data.bak.md5: This file is the Checksum of the previous one, and it is also very important, since it serves to check the values ​​of the previous file. Without this, the previous one is not valid either.
- nv_ta_bin gives: It is neither more nor less than a copy of the main file, of the nv_data.bak. It is not necessary to explain what this file consists of, since it is the same.
- nv_data.bin.md5: This file is the Checksum of the previous one. It does not matter, in principle, if we delete this, since a new one is created the same when we start the smartphone.
- nv_sate t: It is the file whose function is unknown. It is not known what it is for, but if it is deleted, it is automatically created again.
- nv2.bak: This file is only found on Android smartphones with a version of the 2.2 Froyo operating system. It is in charge of managing all the data of the previous files in the version before Gingerbread.
- nv2.bak.md5: Guess. It is only the previous File Checksum, and as such, it is only found on a smartphone with an Android 2.2 Froyo version.
How to modify these files?
Now, it is not so easy to modify these files. Obviously, no user with non-advanced knowledge should make modifications, and for this, they become files that are only accessible with Superuser Root permissions. Even so, there are many users who already have this type of permissions, and who could delete this folder without even knowing what they are doing. Therefore, it is best to explain how they can be deleted and modified, so that you act with knowledge. To modify these files you need a browser with Root permissions, such as Root Explorer, or Root File Manager. Either of these two is valid. You also need to have Superuser permissions. Once we have them, we start the file explorer application, we go to the root folder of the mobile phone, not the SD card, and there we look for the EFS folder. We will quickly locate it, and we can open it. Something that we should do for security is a backup of it. To do this, we only hold down on the folder, select Copy, and paste on the SD card. Later we save the folder on the computer, and in certain places, to avoid losses. In the future, a sudden death, a loss of IMEI, or some related problem could be solved thanks to this backup.
