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I read in this article that a non-encrypted tablet with only screen-lock on can have data read through USB.

Is this really true for example for a Nexus 7 tablet? I mean - if I lock the screen you can't get anywhere, even if you restart the device. Attempts to root it, or to hack it somehow when the bootloader is locked forces a data wipe and a factory reset. So is it really possible to get to the data in a screen-locked Nexus 7 which has no SD card?

The only way I can think about is that someone would somehow open the device and take the internal memory out and connected it somehow to a device which could read it. I presume that would be pretty expensive. If this really is the only way how to get to the data, it might be interesting to know, how much it may cost to do such a thing. If it is really costly, than it should be okay to just use screenlock.

  • What is your question, I'm sorry but I don't understand, is it: 'can you access encrypted data on an android phone?', is it 'can you access data on a non-encrypted android phone with screen lock?', or both, or another question entirely? – ollie299792458 Aug 19 '14 at 10:00
  • Can you access data on an encrypted android phone? No, you can't - not my question. Can you access data on a non-encrypted !Nexus 7! with screen lock? - yes, that is my question. – Ev0oD Aug 20 '14 at 6:58
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    What is the difference between any Android device and Nexus 7? – onik Aug 20 '14 at 7:22
  • Thanks, I believe you can, it depends, did you have usb debugging or root? – ollie299792458 Aug 20 '14 at 10:39
  • Actually, it's entirely possible to get root access without wiping data, if ADB is on. Privilege escalation exploits can do that. – sloosecannon Aug 20 '14 at 20:45
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Basically, as screen lock secures your data as long as the data chip stays in the phone(as long as debugging is disabled [or enabled with no trusted credentials] and the phone isn't rooted), whereas encrypting it secures it no matter what.

Old answer: It is possible to access some data via usb, however other data isn't accessible, plug your tablet into the computer and wee what comes up under internal storage, that is accessible (EDIT: none of it if the screen is locked). Of course given enough time a hacker in possession of your tablet could access all the data (as long as it isn't encrypted) (EDIT: for example as you suggested by removing the internal storage and reading it with a different device).

If your tablet is encrypted none of the data can be accessed without your passcode (if the tablet is switched off).

If usb debugging is enabled or you are rooted it is even easier to access the data.

  • Well, not quite. I tried it out just now, just to be sure I'm not saying something that is not true. If you turn on a screenlocked device, after boot it stays screen locked. If you plug it in via USB, you cannot access ANY data. Yes, the device comes up, but it is entirely empty. After you unlock your screen, the internal storage is shown. Not otherwise. So your data are still behind the screenlock. Given enough time for a hacker is not enough for an answer - it may or may not be true. Leaving USB Debugging enabled is a security hole a user is responsible for and can be avoided. – Ev0oD Aug 21 '14 at 10:12
  • Sorry, didn't notice the screen lock usb debugging disabled thing, however I'm unsure what security it gives to the bootloader – ollie299792458 Aug 21 '14 at 10:58
  • Bootloader itself is secured in a way, that if you have an unrooted device, which was not yet unlocked, you can do nothing but unlock if you wanna do anything else. And unlocking wipes all data. – Ev0oD Aug 21 '14 at 12:08
  • Have updated my answer (which is basically your own answer) – ollie299792458 Aug 21 '14 at 15:26
  • If the data chip leaves the phone, it would only be readable with some special equipment, that could read the memory byte by byte. Is this an expensive thing to do? – Ev0oD Aug 21 '14 at 15:42

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