Anti-theft android system? - Android Q&A, Help & Troubleshooting

Hi there, guys. I don't know if I should ask this here or in the general forum, so... here I go.
I use cerberus in my nexus one since several months ago, and after watching the SassiBoB review of this program, I started to think how could I get it permanently configured into my system, just in case the thief knows how to restore the system configuration of the phone.
She says something about installing it as a system app with... ¿Rom manager?
I can't understand it perfectly, english isn't my mother tongue.
Anyway, I used titanium backup and I was able to get it installed as a system app (I could also add it to the rom zip, but... I know, I'm such a lazy ), so this step is done. Next problem: the configuration. When you do the factory reset, the configuration of the cerberus app is deleted, so it doesn't matter if it's installed or not. It won't work.
Is there any way to keep the configuration in the system, even if you do a system reset?
I know there are several other problems, like the root apps to flash the phone, or even the recovery menu, but I would like to solve all the problems step by step, and I think this is the first one.
Thank you, guys.

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Pretty sure this belongs in the question section.
I don't have it cerb but, my friend told me you go to there website https://www.cerberusapp.com/ and there's a flashable zip you download and install with Rom manger.

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Yes, you are right. In the cerberus web page there is a zip file which contains the cerberus app, so you can flash it as a rom, and it keeps it installed as a system app, but unfortunately there isn't any difference with the other methods. It keeps the app after a factory reset, but the configuration is deleted, so it's like the app isn't installed. I have already sent an email to them asking if there is a way to keep the configuration, but I haven't received any answer yet (and it's new year, it's weekend...).

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OK, step done. They will release another version (2.0) that keeps a copy of the configuration in /etc/system, so if we add the apk and this file to the ROM, it will be safe.
Next step: the app is installed and configured BUT it has to be added to the list of devices administration in the security and privacy option (it has to manage the device). To add it, you must open the app and set the "activate" option, so we have the same problem that we had, so now it's not an app problem, but a ROM problem.
Is there any way to change the apps aded to the devices administrator option? I supose it should be, as the configuration has to be stored somewhere...

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A little step more. I think I found the file where the administration params are stored. It's in /data/system/device_policies.xml
New problem: this file is in the installed system, but I can't find it in the ROM.
¿Any idea? Thanks

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Another hint: I found this:
http://hi-android.info/src/com/android/server/DevicePolicyManagerService.java.html
It seems this is the class who creates the file. It should be easy to modify it so it adds the required data to the file. New problem: I can't find this class in the ROM file. I'll keep searching...

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FOUND!
It's in services.jar, inside the framework directory.
It's necessary to extract the classes.dex, convert it into .jar, extract the DevicePolicyManagerService class and decompile it as java code, and here it is:
Code:
private static JournaledFile makeJournaledFile()
{
File localFile1 = new File("/data/system/device_policies.xml");
File localFile2 = new File("/data/system/device_policies.xml.tmp");
return new JournaledFile(localFile1, localFile2);
}
I think I should be able to modify it. I can't right now, but I'll post it when I try it.

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I was trying to change that java file, but it's a real pain in the ass to recompile it and avoid all the errors. Then I realized that I can just modify the update script to copy the file (yes, I'm such an idiot lol).
I was trying to get it done with the update-script in META-INF/com/google/andriod/updater-script, but I can't get it working. A little help would be appreciated

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Another update (Were you missing me?). I decided to modify the flasheable zip of the cerberus, so it has all the configuration files. I added the data/system/device_policies.xml and also de etc/cerberus_conf.xml files to this zip. Then, I changed the updater:
Code:
show_progress(1.000000, 0);
ui_print("Mounting /system");
run_program("/sbin/busybox", "mount", "/system");
set_progress(0.125000);
ui_print("Mounting /data");
run_program("/sbin/busybox", "mount", "/data");
set_progress(0.250000);
ui_print("Deleting old APK from /system");
delete("/system/app/Cerberus.apk");
set_progress(0.375000);
ui_print("Deleting old APK from /data");
delete("/data/app/com.lsdroid.cerberus.apk");
delete("/data/app/com.lsdroid.cerberus-1.apk");
delete("/data/app/com.lsdroid.cerberus-2.apk");
set_progress(0.500000);
ui_print("Extracting files to /system");
package_extract_dir("system", "/system");
set_progress(0.625000);
--------------ADDED-------------------
ui_print("Extracting files to /data");
package_extract_dir("data", "/data");
set_progress(0.680000);
---------------------------------------
ui_print("Unmounting /data");
unmount("/data");
set_progress(0.750000);
ui_print("Unmounting /system");
unmount("/system");
set_progress(0.875000);
ui_print("Installation complete!");
set_progress(1.000000);
It's a standalone zip file, so you need to flash your ROM and flash this zip file after it. Anyway,
WARNING
This doesn't work. After flashing the second zip file, the ROM won't boot (It keeps booting, with the boot animation in loop). I suppose I break the data directory or something like that. I'll keep trying.

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Yep, I tried several things and the problem is with this line:
package_extract_dir("data", "/data");
It seems it breaks the data directory or something like that. The other files are copied perfectly.

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OK, problem found with adb. With this command, it deletes completely the /data/system directory, so it keeps only the new file. Time to fix it...
EDIT: my fault. /data/system is empty until we start the system for first time. We must flash the rom, boot it, restart and flash the patch with cerberus. This is starting to be kinda stupid... If we do this, we can select cerberus in the administrators menu, instead of flashing anything...

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Last post for the moment with partial conclussions.
When we do a factory reset, it deletes ALL the content of the data directory. So it's impossible to solve this problem just flashing anything after the ROM. Is the ROM who HAS TO COPY the device_priorities.xml into /data/system/. There isn't any other way, it would be erased after a factory reset.
Now, time to find out how to get it done by the ROM. I'll let you know as soon as I get it.

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Work!
I did a full wipe (Wipe Data / Factory Reset + Wipe Cache Partition Wipe Dalvik Cache) and installed the official samsung rom (Android 4.1.2). I installed the flashable ZIP from the site on my galaxy s2 and did not have to reconfigure anything. Everything worked as it should. I believe that the application connects to the user's account based on the information of the device recorded previously.
Avast anti-theft has a Function to protect the configuration after a wipe. Just discover how avast achieves this.
(Translated via google translator)

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That's the one thing is that even Avast and Cerberus won't escape if /system is formatted, but Avast did make it through a full SBF followed by factory reset on my phone.