[GUIDE] get root! - Android Software/Hacking General [Developers Only]

[GUIDE] get root! - Android Software/Hacking General [Developers Only]

Hi all,
this thread would like to be a shortly introduction about root user permission on general android platform!
As we all know the root user in Unix-based OS is the user with UID equal to 0.
Many threads talks about gain root on android by means of magic oneclick tool or by way of flashing custom recovery on device then copy the fantastic ChainsDD's su binary and install superuser or another apk to manage privileged action request .
Do we really need? Probably! But we maybe only want a root prompt, root privilege through adb shell or on the terminal emulator, this is certainly possible.
Deafult android shell is /system/bin/sh, if we could run it through, for example, an executable owned by user with UID 0, and if there was a Unix access rights flags that allow users to run an executable with the permissions of the executable's owner, we probably would get a root shell only by running that executable! Easy!
Only one thing, we should know a method for push our unsecure setuidded executable owned by root under the /system/xbin directory, which is also owned by root!
For example, might be possible to dump our /system, mount the filesystem data on a Linux box (which we know the root password), copy the unsecure elf under the correct path, and then flash back the modified /system image to our device, all with the original bootloader, without any custom recovery.
Once done, if we run the executable, ta daaan....
If someone wants to get his hands dirty:
Code:
void main()
{
setuid(0);
system("/system/bin/sh");
}
this can be enough!

Anyone...?

Related

New Root Security Model?

I saw in the SDK this permission for apps to request:
public static final String FACTORY_TEST
Run as a manufacturer test application, running as the root user. Only available when the device is running in manufacturer test mode.
Constant Value: "android.permission.FACTORY_TEST"
Click to expand...
Click to collapse
Our current model with superuser whitelist is not very secure because a malicious person could bundle their own su binary and circumvent the restrictions. It would seem that having our custom roms run in test mode would provide a great solution: using Android's own permission/security model for apps to run as root. This should force all apps to visibly request root permissions at install time.

I am in favor of anything that will improve the security of my phone. It concerns me that anyone who knows what they are doing can so easily boot into recovery mode on my phone, wipe and flash any ROM they want. Granted, they would not have access to my information if the wipe and flash. But, it makes it trivially simple to hijack my phone. I would like to have some password protection for Recovery and Fastboot.

i am by no means a dev, but it seems to me that this probably just has to do with the adp devices

what's a adp device? and explain how they could possibly do this again?

android developer phone.

jaaronmoody said:
i am by no means a dev, but it seems to me that this probably just has to do with the adp devices
Click to expand...
Click to collapse
well, technically, if we have root, dont have an "ADP" device?
when I do a fresh install, it says welcome to Android Developer Phone 1 (in most ROMs)

the adp device was a specific phone release for developers to be used with the sdk.

jaaronmoody said:
the adp device was a specific phone release for developers to be used with the sdk.
Click to expand...
Click to collapse
I know that, but the hardware is the same as ours (they just get the awesome battery cover)

jaaronmoody said:
the adp device was a specific phone release for developers to be used with the sdk.
Click to expand...
Click to collapse
Most roms especially cyanogen Roms are based on SDK/ADP1 directly and thus making our devices recognizable as ADP Devices.

Simple solution could be to restore the original su binary at boot.
1) keep a copy in the boot image ramdisk
2) scan the path at boot for su
3) compare md5sum with the original
4) delete if md5sum is different
5) restore original trusted su
and also just for paranoia:
6) scan system for setuid binaries and report to the user

This has NOTHING to do with ADP1. Test mode is just that... TEST MODE, i.e. diagnostics and repair. Probably needs to be plugged into a test station that authenticates using some manufacturer diagnostic keys. I really doubt that it would be a simple matter of requesting root permissions as this would be too easy to abuse.
And to the OP: No, you can't just bundle an 'su' binary and run it. The binary has to be owned and setuid as root in order for it to actually get root permissions. There is nothing magical about the su binary -- it is just 'sh' renamed as 'su', chown'd as root, and chmod 4755. A regular user can NOT chown root. Only root can chown root. Note that the su binary that works with the root app is modified such that it will terminate if the root app doesn't grant root permission. For all these reasons, su+rootapp is fairly secure. Not against someone unauthorized getting their hands on the device, but against some malevolent app taking root and running amok.

lbcoder said:
This has NOTHING to do with ADP1. Test mode is just that... TEST MODE, i.e. diagnostics and repair. Probably needs to be plugged into a test station that authenticates using some manufacturer diagnostic keys. I really doubt that it would be a simple matter of requesting root permissions as this would be too easy to abuse.
And to the OP: No, you can't just bundle an 'su' binary and run it. The binary has to be owned and setuid as root in order for it to actually get root permissions. There is nothing magical about the su binary -- it is just 'sh' renamed as 'su', chown'd as root, and chmod 4755. A regular user can NOT chown root. Only root can chown root. Note that the su binary that works with the root app is modified such that it will terminate if the root app doesn't grant root permission. For all these reasons, su+rootapp is fairly secure. Not against someone unauthorized getting their hands on the device, but against some malevolent app taking root and running amok.
Click to expand...
Click to collapse
Thanks for clearing that up.
The idea posted earlier about recovery menu password should be lofted at Cyanogen (or anyone willing to take that on). Should we make a thread for it?

Keep in mind that it is physically impossible to secure your phone against somebody who gets their hands on the actual device. You can only make it harder to get at it. If somebody wanted to they could just read the flash chip directly or use JTAG to get at it. However, I agree that adb could be made a bit more secure.

And to the OP: No, you can't just bundle an 'su' binary and run it. The binary has to be owned and setuid as root in order for it to actually get root permissions. There is nothing magical about the su binary -- it is just 'sh' renamed as 'su', chown'd as root, and chmod 4755. A regular user can NOT chown root. Only root can chown root. Note that the su binary that works with the root app is modified such that it will terminate if the root app doesn't grant root permission. For all these reasons, su+rootapp is fairly secure. Not against someone unauthorized getting their hands on the device, but against some malevolent app taking root and running amok.
Click to expand...
Click to collapse
@lbcoder,
That's nonsense. Check any linux system, /bin/sh is always owned by root and is always executable. Running an executable owned by user X does NOT run said program as X. Copying a binary onto the phone preserves permissions, so if i chowned an sh binary as root on my computer and copied it over, the binary will stay owned by root. The su binary is just that, a binary. It is not simply a shell owned by root.

nobodyimportant said:
@lbcoder,
That's nonsense. Check any linux system, /bin/sh is always owned by root and is always executable. Running an executable owned by user X does NOT run said program as X. Copying a binary onto the phone preserves permissions, so if i chowned an sh binary as root on my computer and copied it over, the binary will stay owned by root. The su binary is just that, a binary. It is not simply a shell owned by root.
Click to expand...
Click to collapse
you're missing the bit (pun intended) about su being setuid root. when a normal user runs su, it does, indeed run as root, but it uses the security subsystem behind the scenes to prevent unauthorized activity:
http://en.wikipedia.org/wiki/Setuid
the 'unzip' executable will, indeed, preserve ownership, but to my knowledge, there's no way to copy a setuid binary to the phone as a normal user -- there may be a way it could be pulled off, but I don't know how

nobodyimportant said:
@lbcoder,
That's nonsense. Check any linux system, /bin/sh is always owned by root and is always executable. Running an executable owned by user X does NOT run said program as X. Copying a binary onto the phone preserves permissions, so if i chowned an sh binary as root on my computer and copied it over, the binary will stay owned by root. The su binary is just that, a binary. It is not simply a shell owned by root.
Click to expand...
Click to collapse
I have one thing to say to you:
http://en.wikipedia.org/wiki/Setuid
Now that you've made a complete and utter fool of yourself, how do you feel?
FYI: your regular user can NOT chown root. Go ahead and try it.

alapapa said:
you're missing the bit (pun intended) about su being setuid root. when a normal user runs su, it does, indeed run as root, but it uses the security subsystem behind the scenes to prevent unauthorized activity:
http://en.wikipedia.org/wiki/Setuid
the 'unzip' executable will, indeed, preserve ownership, but to my knowledge, there's no way to copy a setuid binary to the phone as a normal user -- there may be a way it could be pulled off, but I don't know how
Click to expand...
Click to collapse
It is a moot point whether the setuid bit can be restored since a regular user doesn't have the ability to change the owner to anything but self, which means that the best they could do is create an su binary that will give other users THEIR OWN permissions.
A regular user can change ownership *only* to self -- i.e. if they have group or other write permission, then they can chown the file. They can also change the group, but only to groups to which they are members -- and this requires that they already have some form of write permission on the file.
Note that extracting a file is no different than actually *creating* the file, which means that if the user couldn't simply MAKE the file, then they can't *extract* the file either.
If any of this was untrue, there would be nothing to stop any user from doing something like this to take over any Linux computer (except from within a chroot jail, but that doesn't apply here);
cp `which sh` ~/su; chown root:root ~/su; chmod 4755 ~/su
** but that most definitely won't work.

[Q] Linux command-line rooting

I've searched through the forums, and could not find an answer.
I'm familiar with Linux and Unix system administration, so I am more comfortable with using command line interfaces to move files around. This should make it fairly straightforward to root my wife's Skyrocket while maintaining a stock root. I know that it basically involves installing the superuser APK, moving the su command file and expanding the busybox files into /system/bin. The problem is that /system/bin is owned by root, and that it is also read-only. To my knowledge, the stock Skyrocket is locked.
My question is - does the fastboot OEM unlocker allow me to remount /system as read-write as a normal user, or is there another way to do this on a Linux command line?

[ROOT][SamPWND][N960U][WIP-Combo Needed]

Hello XDA!
Samsung has been semi SamPWND again!
Disclaimer:
This root method was developed and tested on the N960U model. This is the only model I have that is a Samsung device. I do have friends and other devs however that have tested this method on various other Samsung devices on both Qualcomm and Exynos chipsets and it has worked on a good number of them meaning this method is not limited to the Note 9. With that being said, due to all the time I have already spent on this and not having any other devices, I will ONLY be supporting the N960U. So do not get upset if I do not respond to you if you have a Samsung A8934839K312 on 7.1 Android (aka a device I have never even heard of before.)
Disclaimer 2:
This root method is mainly for dev's or those who like to tinker and figure things out. The reason I say this is because at this time, you are REQUIRED to be on a factory/combination firmware to mess with the root method. I will ignore any comments/questions for people who do not read this disclaimer and ask me how to root stock etc. as that is what I have been trying to do for over a month now. If you need your phone for work or a daily then I suggest only messing with this root method if you have a lot of spare time since it involves flashing combo firmware at which mobile services and other stuff will not be functional. You have been warned!
Disclaimer 3:
This thread/poc are essentially to get you the ability to use root apps and have a root shell, that is it. If I have time and see some questions that are legit questions I will try to provide help in a timely manner. This POC simply pushes busybox binary from Magisk.zip and SuperSU (the last version chains released before retirement) and installs it in sbin/daemon mode. There is also a way to install MagiskSU in daemon mode as well as ways to install root to /system/xbin for example and do mods such as Xposed that typically need to modify the system partition but that is not the purpose of this thread and these methods are a bit more involved (require modifying the root script as well as setting up bind mounts and other stuff.) Hopefully once this is released and some devs chime in I hope there will eventually be others contributing with various root scripts, install methods etc. and of course HOPEFULLY find a way to write to system/odm/vendor partitions so we can eventually run root on stock!
Disclaimer 4:
I am NOT responsible if you break your phone, wipe your IMEI, hard brick etc. etc.! Also, I spent months to get to this point and already had someone steal my files from AFH (I know, my fault for not hiding them) so please do not take my work as your own. If you want to use it in any way/shape/form just ask for permission and/or give credits in your thread is all I ask! If you are however using someone else's modified files and in here trying to get help I might turn you away (back to the person who provided the modified files) just an FYI!
I think that is enough disclaimers for now!
Note: This thread will most likely be ugly for a bit as I am terrible with making these things look pretty... Hopefully as time goes I will keep improving it or find someone who is trustworthy I can make a "contributor" so they can fix it up for me haha.
Now, Let's Get To It!
Technical Details:
This is sort of a spawn from an exploit I found and reported to Samsung back on the Tab S3 that I never released on XDA. That method (long story short) involved modifying the Persist partition and flashing it in ODIN as ODIN did not check it for integrity. Of course it was patched by Samsung who gave me some $$$ and gave me a shout out on their security bulletin which was pretty cool!
This method is similar to "Persist Root" except we are not flashing any modified partitions in ODIN. Instead, on many Samsung combination firmwares there is an init rc script on /system. If you want to know if your device is compatible a good starting point would be to look for a file called "init.lab.rc" which is typically located at "/system/etc/init/init.lab.rc" like so:
-rw-r--r-- 1 root root ubject_r:system_file:s0 14784 2008-12-31 10:00 init.lab.rc
As it stands, we cannot edit this script. I noticed something cool however when I was reading it one day. Specifically one thing that caught my eye was this:
chmod 777 /data/lab/run_lab_app.sh
There are MANY files and scripts at /data/lab. Luckily, the init.lab.rc sets permissions to "0777" and sets ownership to system on the entire /data/lab directory! If you are still with me, this means all the contents of this directory are world readable/writeable and we can modify any of the files in this DIR without elevated privileges!
Now I am showing the "run_lab_app.sh" script specifically for a reason. We know we can modify any scripts on /data/lab, but how can we execute it with elevates privileges? Going back to the init.lab.rc, if you scroll to the bottom of the rc file you will see this:
service start_abc /system/bin/sh /data/lab/run_lab_app.sh factory abc+
user system
group system
disabled
oneshot
on property:sec.lab.abc.start=1
start start_abc
setprop sec.lab.abc.start 0
Now what that means is, when you set the property "sec.lab.abc.start" to "1" it executes the abc service as system user and more specifically it will start by executing the "run_lab_app.sh" script! Therefore, after you modify the script to your liking, push it to /data/lab/run_lab_app.sh, then do a "setprop sec.lab.abc.start 1" your script will be executed as system user!
Now system obviously is not "root". Now that we can execute as system user we have more attack vectors to elevate privileges even more. Ideally, I remembered how I rooted the Tab S3 about a year ago using Persist partition. As it stands, we are not able to read/write on persist. If we were to set permissions however on /persist using the run_lab_app.sh script, then we can gain access to it! Therefore, one would only need to add this command to the run_lab_app.sh script and execute it using the setprop command:
chmod -R 0777 /persist
As soon as you modify the script, push it and execute the setprop command, it will change permissions on the /persist DIR to be world readable/writeable!
Now, the reason why I like to use Persist, there is a script that is executed by INIT on every reboot automatically (this means it is executed by root!) The script in question is this one "/persist/coresight/qdss.agent.sh." (I am not sure if this script itself is a Qualcomm specific script or not.) Modifying this script has no ill effects on anything from what I have seen.
Now to see how the script is executed you can look in "/vendor/etc/init/hw/init.qcom.test.rc" and you will see some interesting stuff including this:
crownqltesq:/vendor/etc/init/hw # cat init.qcom.test.rc | grep persist
service cs-early-boot /vendor/bin/sh /persist/coresight/qdss.agent.sh early-boot /vendor/bin/init.qcom.debug.sh
service cs-post-boot /vendor/bin/sh /persist/coresight/qdss.agent.sh post-boot /vendor/bin/init.qcom.debug.sh
write /persist/coresight/enable 1
write /persist/coresight/enable 0
crownqltesq:/vendor/etc/init/hw #
As I stated earlier, due to this init script, the qdss.agent.sh script is executed by init context/root user automatically during early boot and post boot. This means once you get everything set up, you won't need to keep reinstalling root (unless you mess something up) on each reboot. This is ideal since we don't have a way yet to modify system/vendor/odm partitions yet. Think of it as a "systemless" root.
For the POC I have provided in this thread for example, it contains the bare minimum SU files. The files in the attached zip are simple: SamPWND.bat, sampwnd1.sh, sampwnd2.sh, /sampwnd which contains su, sukernel, supolicy, libsupol.so and busybox. The way it works is this:
1) You double click the .bat file and it should do everything for you! The .bat file will:
- Push sampwnd1.sh to /data/lab/run_lab_app.sh
- Execute the lab script by doing "setprop sec.lab.abc.start 1"
- Push sampwnd2.sh to /persist/coresight/qdss.agent.sh
- Push root files in "sampwnd" folder to /persist/coresight/sampwnd
- Set permissions on the files we just pushed to Persist to 0777
- Reboot the device (Note: The .bat file reboots the device at this point since everything is in place to root when the device reboots, it's that simple!)
After the device reboots, you should now be able to use a root shell as well as sideloading any root apps will work (apps such as TiBu, Root Explorer, Flashfire etc. etc.)
When the device reboots, the qdss.agent.sh script does the following automatically:
1) Mounts rootfs and sets permissions to 0777 so we can access /sbin
2) Pushes the contents of the root files folder "sampwnd" to /sbin
3) Sets permissions to the files we just moved to /sbin
4) Exports the LIB path to /sbin due to the libsupol.so being needed to patch the sepolicy with supolicy
- The export command is "export LD_LIBRARY_PATH=/sbin"
- Once the script is over and you use another app or go into a shell etc. the LIB path will be gone/reset so you don't need to
worry.
5) Patches the sepolicy for SU
6) Installs SU by executing "su --install"
7) Executes the SU daemon by running "su --daemon"
8) Lastly, remounts rootfs back to RO.
As stated earlier, these commands are all automatically executed by init/root each time you reboot the device. Essentially, whatever we put into the qdss.agent.sh script will be executed on boot by init/root. If for some reason permissions are lost, we should still have our lab script and we would only need to run "setprop sec.lab.abc.start 1" to change permissions on persist again!
The initial files I provide today are just a simple root install script. I have successfully used the root script to install MagiskSU, Xposed (using bind mounts to overlay on /system) and other tests. I also at one point made a backup script that backed up all the partitions on the device into a folder which I extracted to my PC for safe keeping, you get the picture! Once you have root however, you can do these things easier as you will have root access.
Now that you know the workings of the exploit (err exploits?) I will explain briefly what is needed and how to test it.
Pre-requisites:
1) Download links will be in 2nd post.
2) For the purpose of this thread and the only device I personally have, you should have a N960U/U1/W on a rev1 bootloader (there isn't a rev2 BL yet so most should be good to go.)
3) A vulnerable Combo Firmware. I linked the one I use in Post 2. I use 1ARG4 Factory/Combo firmware. Of course you will need ODIN to flash the combo.
4) The root files/7z linked in post 2.
5) Stock firmware for when you are done playing, testing, etc. etc.
6) Almost forgot, you will need ADB. I will not go into details on this, if you don't have a working ADB Google is your friend. I recommend setting it to your path so you can use ADB from anywhere on the PC.
Install Instructions:
1) Extract the root files 7z into a DIR of your choice.
2) Flash whichever vulnerable combo firmware you are using via ODIN.
3) Once it boots up, make sure your device is seen by adb by running "adb devices"
4) Double click the .bat file.
5) That's it! Your device will reboot and you should be rooted!
If for some reason it is not working and you are on a N960U/U1/W, there could be a number of reasons. If you are not using the 1ARG4 combo I linked then it's possible the combo you are using is not vulnerable. It could also be an issue with ADB. Sometimes if things get crazy throughout your testing you might need to reflash /persist in ODIN or reflash the combo firmware in ODIN then re-run the .bat file (I only experience this typically when I get crazy with the root script and end up losing permissions to everything or something I added in the root script is causing the device to boot-loop etc. etc.)
Now donations are not required but feel free to throw me some beer money if you want! My paypal email/link is in a few places, you shouldn't have any trouble finding it!
TELEGRAM GROUP IS COMING REAL SOON!
We will use the TGRAM to provide support, ideas, share scripts/files and HOPEFULLY, we can all figure out together how to turn this into rooting the stock firmware as this is the goal and will be the primary focus of the chat!
Credits:
@samsung - for letting us PWND them time and time again!
@chainfire - SuperSU of course
@topjohnwu - MagiskSU of course
@me2151 - For all the time and help he is going to be putting in with us! Such a great guy! lol
@jrkruse - For everything! Everything from EDL support, ROM support, Root support you name it!
@partcyborg - For also spending countless hours helping answer questions in here so I don't have to hahah
@mweinbach - He writes great articles for XDA! He is a good kid who gets his hands on cool things frequently
@"mysecretfriendfromfaraway - I will not name him haha, he knows who he is. He always helps out and gets great things!
XDA:DevDB Information
SamPWND N960U Root, Tool/Utility for the Samsung Galaxy Note 9
Contributors
elliwigy
Version Information
Status: Testing
Created 2019-05-05
Last Updated 2019-05-05

[ROOT][SamPWND][N960U][WIP-Combo Needed]

How do I temporarily root a samsung device running android 9 without twrp recovery?

I have used magisk to patch the file and android platform tools (fastboot or stuff like that) but it does not work. I dont want to install twrp as i dont really trust custom recoveries as much and i dont want to use odin for the same reason. Is this impossible or is there a way but i am just doing it incorrectly. Please reply asap!

Never installed Magisk nor TWRP, why should I have done it?
To answer your question: A temporary root can get achieved by putting a suitable su into directory /data/local/tmp and making it executable.
https://forum.xda-developers.com/attachments/su-binaries-zip.5566949/

xXx yYy said:
Never installed Magisk nor TWRP, why should I have done it?
To answer your question: A temporary root can get achieved by putting a suitable su into directory /data/local/tmp and making it executable.
https://forum.xda-developers.com/attachments/su-binaries-zip.5566949/
Click to expand...
Click to collapse
The data partition is not accessible without having root first. How are they to place su in data partition to gain temp root without first gaining root to place su in data partition? How can they root the device by using a method that requires root in the first place to achieve what you are telling them?

I think the code
Code:
adb push <PATH-TO-SU-ON-PC> /data/local/tmp
always works , because this path ( /data/local/tmp ) is always present and writable on Android dev device and Emulator.
At least it always worked for me since I'm rooting Android this way.

xXx yYy said:
I think the code
Code:
adb push <PATH-TO-SU-ON-PC> /data/local/tmp
always works , because this path ( /data/local/tmp ) is always present and writable on Android dev device and Emulator.
At least it always worked for me since I'm rooting Android this way.
Click to expand...
Click to collapse
do i unroot my device by rebooting it?
p.s. will doing this solution create a possibility of bricking my device?

Technically seen you can't root / unroot a device, but only Android OS.
As with Android OS root ( sometimes called superuser ) is the same as Administrator with Windows OS. Simply adding an user with elevated privileges never will brick an Android device.
Become familiar what root is the world of Linux OS - take note that Android OS merely is a port of it.

xXx yYy said:
Technically seen you can't root / unroot a device, but only Android OS.
As with Android OS root ( sometimes called superuser ) is the same as Administrator with Windows OS. Simply adding an user with elevated privileges never will brick an Android device.
Become familiar what root is the world of Linux OS - take note that Android OS merely is a port of it.
Click to expand...
Click to collapse
so running that command will give me legit root privileges and i can do the things an admin can do without any malware or damage?

Droidriven said:
The data partition is not accessible without having root first. How are they to place su in data partition to gain temp root without first gaining root to place su in data partition? How can they root the device by using a method that requires root in the first place to achieve what you are telling them?
Click to expand...
Click to collapse
so should i really use magisk to root my device?

moutsu said:
so should i really use magisk to root my device?
Click to expand...
Click to collapse
No, try what was suggested by placing su in the data/local/tmp. If that doesn't work, try using magisk to root your device.

xXx yYy said:
I think the code
Code:
adb push <PATH-TO-SU-ON-PC> /data/local/tmp
always works , because this path ( /data/local/tmp ) is always present and writable on Android dev device and Emulator.
At least it always worked for me since I'm rooting Android this way.
Click to expand...
Click to collapse
I've never seen a device rooted by such simple means, in my experience, it has always required root to even access data partition, especially if trying to push/pull files to/from data via adb.
I mean, if it were really that easy, why would all these rooting tools snd methods that exist on XDA have ever been needed to be created?
What devices have you rooted using this method? Can you provide information that explains and confirms what you say?

Hmmmm...
Short checked on my SM-R860 Android 11...
Code:
freshbs:/ $ cd /data/local/tmp
freshbs:/data/local/tmp $ ls
freshbs:/data/local/tmp $ ls -a1l
total 6
drwxrwx--x 2 shell shell 3452 2022-03-25 01:20 .
drwxr-x--x 4 root root 3452 2022-03-25 01:20 ..
Need more time or drinks to place something here...
Waiting for other results...
Best Regards

@Droidriven
Fellow member @adfree has proven that even with Android 11 directory /data/local/tmp worlwide exists and is writeable.
Sometimes it really makes sense to understand what OP wants to achieve: He just wants to know how Android can be temporarily rooted.

xXx yYy said:
@Droidriven
Fellow member @adfree has proven that even with Android 11 directory /data/local/tmp worlwide exists and is writeable.
Sometimes it really makes sense to understand what OP wants to achieve: He just wants to know how Android can be temporarily rooted.
Click to expand...
Click to collapse
I do need to know how an android can be temporarily rooted so I can give certain apps on my phone root access to recover some stuff I accidentally deleted. However, I do need a bit of clarification on what su file I need to put into the directory as the filed you linked was a zip file.
I would also like a method on how to unroot my device.

Dear moutsu...
IMHO instead blabla... IMHO it makes sense to start from scratch with FULL infos.
I can see only bla bla Samsung Device...
Please give full details...
A
Model Name...
Example:
SM-G920F is Android 7 for instance...
B
Is Phone alive... then give full details about Firmware Version.
Easiest way for most infos...
Type:
*#1234#
Type or make Photo or Screenshot...
Best Regards

@xXx yYy
Thank you very much. But...
I clicked through your profile and find some more puzzle parts of your idea...
Learning to root my old Galaxy S4
I have an old Samsung Galaxy S4. It's been off the network for a while and its system clock has drifted. However, adb works and I can use the old phone as a sandbox environment to learn about low level Android fundamentals. I would like to learn...
forum.xda-developers.com
After this I was drunken enough to try few things with my SM-R860...
WITHOUT success...
Later I will add my ADB output... for better understanding...
IMHO I am not total Noob in Rooting something...
Also I have "some" experiences in recover halfdead devices to backup beloved data...
I am sure you have forgotten about Samsung additional Security check... like Knox crap etc...
So my conclusion...
Your method is good to know...
But chance for success in "newer" Samsung devices is not 100 %...
Maybe you can give Samsung model name... where this work?
I could check SM-G920F with Android 7 just for fun... if I have time...
Thanx in advance.
Best Regards

regardless it is writeable to adb shell only (uid 2000), chown is forbidden anyway. even if you set SUID bit that wouldn't make much sense in /data/local/tmp
furthermore, even if you could place su binary in /system (which requires unlocked bootloader + dm-verity patch) it still requires privileged daemon in background where su want connect apps (but not exist).
so this method never worked, except for some ancient android devices where remount /system was possible from adb root.
and we haven't spoke about selinux, yet
Magisk does all this, but requires* unlocked bootloader - which triggers factory reset. So unless you have some nice exploit like dirty-cow or mtk-su, temporary root is simply impossible.
edit: TWRP is not able to decrypt samsung encryption btw. So if you want have access to userdata partition on locked bootloader the only way would be (samsung signed) so called "combination ROM" (with same bootloader level) to be flashed from Odin via HOME_CSC or heimdall.
if your device is ancient old you might lucky bootloader is unlocked, userdata partition is not encrypted at all, and ROM is just signed with test keys. in that case you can flash anything on recovery partition. philz touch recovery even provided flashable zips that signed with test keys, these zips can be flashed straight from stock recovery without PC. I remember temporary zips exist, that only boot into custom recovery without actually installing it.
edit2: *except some Mediatek devices with AVBv1 where one can flash magisk patched boot.img on locked bootloader

My last 2 cents here ( I no longer participate this thread ):
The su ( read: switchuser ) command is used to run an Android system function as a different user. It is the easiest way to switch or change to the administrative account ( read: superuser ) in the current logged in session.
Most versions of Android disable the superuser ( mostly mistakenly called root user - take note that root user in Android is the user with ID 0 who is by default present on all Android versions, is the user of session when Android gets started ) account by default making the system more secure. But, this also restricts the Android user from running specific system related commands.
Using su to temporarily act as a superuser allows you to bypass this restriction and perform system related tasks with different users.
The synthax of su command is
Code:
su [options] [username [[arguments]]
If a username isn't specified, su defaults to the superuser. Now, the logged-in user can run all system commands. This will also change the home directory and path to executable files.
If the su is used to temporarily act the logged-in user as superuser then the su binary can be located anywhere in Android's filesystem, e.g. /data/local/tmp, /storage/emulated/0, etc.pp, it must not be located in Android's system partition.

xXx yYy said:
My last 2 cents here ( I no longer participate this thread ):
Click to expand...
Click to collapse
yes, that's maybe better. teach yourself about android first. android is not linux
What special privileges "/system/xbin/su" does have w.r.t. root access?
This answer says: Because of the way directory/file permissions are configured on Android, you need to have the su binary on your /system partition in order for it to work. Putting elsewhere...
android.stackexchange.com

what is your current bootloader level? combination ROM is available (haven't checked these download links)
https://www.samsungfirmwares.info/samsung-sm-j415gn-combination-firmware-file-rom
my expectation ro.debuggable=1 is enabled
adb root will work on eng build

aIecxs said:
yes, that's maybe better. teach yourself about android first. android is not linux
What special privileges "/system/xbin/su" does have w.r.t. root access?
This answer says: Because of the way directory/file permissions are configured on Android, you need to have the su binary on your /system partition in order for it to work. Putting elsewhere...
android.stackexchange.com
Click to expand...
Click to collapse
Yeah, I get where they were coming from but.....
Nah. It just doesn't work that way for everybody. Like all things android, it really just depends on what device you have and how crappy its hardware/software and security is. Lower end/cheap and old stuff doesn't have as much time invested in making them secure to save on development and distribution costs.
Unfortunately, Samsung just isn't one of those brands that are easily rooted these days, unless you buy specific models with specific firmware/binary combinations.

Database Info

welcome