[Q] How to gain root access, if busybox and system app is already installed?
I have a Rockchip RK3188 Tablet with Android 4.2.2, which I need to root ON DEVICE. Actually, the device was already rooted (using a Laptop via the adb bridge), so I already have busybox installed and I have one of my own apps in /system/app. However I managed to delete the su program (yeah great!) and therefore don't have root access any more. I know I can easily root the device again if I connect it to my laptop again, but that is not possible, because the device is at my parent's place and I can't go over there any time soon.
Therefore I want to root the device just with an app. Actually I would only need to copy su to /system/xbin.
These are the things I already tried (without success):
- Framaroot (doesn't work, because framaroot does not support Rockchip tablets)
- Writing my own app, which contains su in the assets and using this su for temporary root
- Using adb (on the device) for a local connection (adb connect localhost), because if I connect from my PC I automatically have root (doesn't work because Android 4.2.2 has increased security on adb)
- Start telnetd via busybox and then execute my commands via nc (doesn't work, because I can't start telnetd in a way that it ends up with a root shell)
Any other ideas?
My last idea is, that I could maybe gain temporary root access with the app I already have in /system/app. Basically this would be similar to the Master Key Exploit, except that I do not have to fiddle around with the apk and instead install it normally. However I don't know how to continue from that point. I know, I have special permissions if I have an app in /system/app, but which permissions are that? And how can I use those permissions to make /system writeable (and copy my su file there)?
Thank you for your help,