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Usually if your device is stolen the first things a common thief is going to do is : Disconnect the devices from networks and wipe it out so he can resell it.

Here is the current setup i imagined to theft-protect my Android device against common thiefs.

  1. Bang up the volume buttons so booting into factory reset mode isn't possible anymore. - don't worry you can replace them with a volume control app -

  2. Disable USB debug mode.

  3. Install an app locker which password protects the 'Settings' menu which can be used to enable USB debug mode and sometimes factory reset the device.

  4. Install a stealth phone tracking app or your own malware which leaks GPS location and other usefull information by SMS if the attacker put on a SIM card or throught the internet if he connects to Wi-Fi.

What usefull informations could be retrieved ? LAC/CID, MSISDN, GPS coordinates, IP Address. On top of that, a RAT would allow mic and camera spying. We could leave some apps accessible for the thief to leak informations about himself.

Optionnal : Encrypt all the data to keep a more advanced thief with different goals to access your data.

These mesures leave the attacker with a locked-up device which he can't connect to any network, nor wipe out. Eventually he will become desesperate and connect to a network which will give away informations.

What do you think of this setup ? How would you manage to wipe out my phone anyways ?

Edit : In case the thief incredibly manages to wipe out the device, their's two tracking / anti-theft apps who persist even after factory reset, Avast Anti-Theft and Cerberus. You can also move your own tracking app / malware to system partition through root. Alnernativly, you can turn on Android own anti-theft protection which demand you login to your google account after factory reset

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    "What do you think of this setup ?" -- I think that it's a Hollywood movie plot, other than point #2 (which isn't relevant for most users anyway). If you are worried about the cost of the phone, use a cheap phone or obtain some form of insurance for it. If you want to keep people out of your data, use a decent system lockscreen PIN or passphrase, perhaps with a device administrator app that will automatically wipe the device after N failed attempts. Law enforcement might try creating a honeypot device like you describe.
    – CommonsWare
    Jan 22, 2017 at 13:04

2 Answers 2

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Optional : Encrypt all the data to keep a more advanced thief with different goals to access your data.

This is not optional, encryption is the #1 must have. I assume that you care about keeping your device secure because you want to keep your data secure, over making it harder for the thief to take use of the phone. If it's stolen, it's stolen, most likely you will not get it back, even if you could somehow track the thief with these applications, law enforcement will not be fast enough to catch whoever stole it and you wont go down the rabbit hole by yourself.

Also there's no bulletproof solution for preventing the manual reset of everything on the phone.

A professional thievery scenario looks like this:

  • the phone is stolen, the battery and sim card get instantly removed
  • if it's not possible to remove the battery in place, the phone is wrapped into some kind of insulation or put in a metal container
  • the device is taken to a well insulated place (possibly some cellar, again tested for no rays coming in and out)
  • it is disassembled in place, or the kernel gets reinstalled in place

Be vigilant and don't get your phone stolen. That's the best advice I can give you, and of course if storing sensitive data on the device, encrypt it (not with some fancy google play application), you should enter the decryption key on boot time.

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  • How would you reinstall the kernel ? Remember USB debug mode is off and you can't access the menu to set it on. Can't hard reset the phone neither because volume up key is banged up. So, how ?
    – diabl0
    Jan 22, 2017 at 18:24
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    If you remove or make the volume control keys inoperable, the circuit is still behind it, just touching with a wire may be enough to mimic what the keys would do. You wouldn't remove the original IC, would you? To your question, yes, you made it harder for them, but the possibility of reusing the phone is always there, you can't do anything about that.
    – Rápli András
    Jan 22, 2017 at 23:50
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If an attacker knew your setup (or was just playing safe), he would try the following things:

Assuming your phone is of sufficient resale value (i.e. worth buying the replacement parts for)

  1. Immediately disassemble the phone to take the battery out. Manually short or replace the volume up key to boot to Recovery Mode. As far as I know, no common Recovery supports telephony for calling home.
  2. Wipe the phone (all partitions). Game over. No app can survive that.

If the attacker was unsure of whether he would be able to reassemble the phone afterwards, he could wrap it in aluminium foil or put it in any other Faraday cage to prevent it from connecting to any networks. If the attacker decides it's not worth the effort, he can simply destroy the phone.

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  • Hi, thanks for your answer. I don't think you can wipe system partition, can you ? That's where Avast Anti-Theft and Cerberus would sit. Also, if i burn the surrounding of the volume up key, do you think it's still can be repaired ? Anyways, can TWRP password protect hard reset through volume up key ? The worst case scenario is no one can use the phone (he leaves it in a faraday cage or just destroy it), but still if you do all these things you have a chance to get back your device and you make phone stealing an useless practice.
    – diabl0
    Jan 22, 2017 at 13:32
  • You can definitely wipe the system partition. In fact, this is normal practice when installing a new ROM. Also I made a mistake in my answer, if you password protect the Recovery, an attacker can simply flash a new one. You can protect your data with full disk encryption, as is offered in all recent android versions. As to the security of the device itself: if an attacker has physical access, all bets are off. As to the volume buttons: they can always be replaced when destroyed. They're just mechanical buttons.
    – Jenessa
    Jan 22, 2017 at 13:45
  • Ok, so the thief must be vigilant enough to reflash the ROM after doing a factory reset which is by not enough by itself to remove the trackers. Since he can't reflash the ROM until he factory reset the device and since every other reset feature on the phone is locked by password, the whole success of this operation depends on whether or not he can repair the volume up button, right ? That could be kind of hard after i murder that part of the circuit and maybe put some kind of paste inside the volume up key hole. It's kind of extreme, but that would in fact make the device secure af.
    – diabl0
    Jan 22, 2017 at 14:07
  • No! You won't get your phone back after someone steals it. If you want to discourage people from stealing it, sure, ruin the volume buttons. If you want to protect the data that is on there, use encryption with a strong key. Being unable to easily boot to recovery without a few minutes of scrubbing some paste off some electrical contacts does not make your phone "secure af".
    – Jenessa
    Jan 22, 2017 at 14:33

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