NSA Tracks Turned-Off Phones — But Phone Makers Don't Know How

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gggplaya

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It's literally impossible to track a powered off phone. The operating system is not functioning, the cellular signal is not active, the circuits are powered down.

However, it is possible to install a software program to make the user think the phone has been powered off. When they press "power off", it visually gives them an indication that it is booting down, but in reality is still running.
 

InvalidError

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"Powered Down" might be a relative term: do phones actually have a MOSFET that physically breaks electrical continuity between the power source and RF chips or do phones rely on the RF ICs themselves to manage their own power?

If the RF ICs are managing their own power, it would be possible for Broadcom, Qualcom, etc. to have their own reporting routine in their RF chips' firmware that powers up independently from the main CPU/OS.

So there is at least one way it could happen.
 

figgie

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For all Intents and Purposes... the receiver is off.

but it is simple RF. regardless if it is off or not, send a strong enough signal and it will resonate ;) the military application has been there for ever... don't query the object, query the oscillator.

Now the question is filtering the noise out.

Let me put it to you this way. We were able to track powered off radar speed guns in patrol cars.
 

Baldarhion

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Yes InvalidError. And even without battery, some capacitors couls do the job too.

Well... I guess the only option is a a microwave oven: (yes, luckily, it's wave proof, so
pizza Industry will be a pain in the a** for the NSA and save our privacy, i suppose...
 

realibrad

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I thought this was already assumed? Here is an ABC article about how the FBI can listen in on phone calls, even when the phone is off.

http://abcnews.go.com/blogs/headlines/2006/12/can_you_hear_me/
 

razor512

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It depends in the phone is able to still periodically power on the cell radio, but I guess that will be spotted during the fcc test. Other than that, the only way to track a device is if you are very close and it has some kind of RFID, or something else that can respond to RF without having a local power source. Most cities have a wide range of RFID trackers for collecting traffic data, though there is nothing saying that they cannot track other things that can respond to a similar fashion to RFID

PS modern smartphones never fully power off, if you run it through a multimeter, you will see that even when powered off, they will pull quite a few microamps (though it may be for the soft power switch, clock and other needed components to listen for that button press)
 

cgharvey

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what happens when you phone is off and you get a call? It says the phone is off.. so..im guessing they can "ping" your phone.. Yes? because you get back a message the subscriber can not be reached.
 

MPrice

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"what happens when you phone is off and you get a call? It says the phone is off.. so..im guessing they can "ping" your phone.. Yes? because you get back a message the subscriber can not be reached."

How about the concept that your phone can be assumed to be off because it cannot be pinged? Makes a bit more sense right?
 

koga73

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Figgie's comment sounds about right.
but it is simple RF. regardless if it is off or not, send a strong enough signal and it will resonate the military application has been there for ever... don't query the object, query the oscillator.
Something else to consider is the phones GPS. GPS satellites are constantly beaming down signals and normally the device would triangulate its position. It seems possible that the GPS signals could "bounce" off a GPS chip or create some sort of interference even if powered down.
 

coolitic

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However, both Ericsson and Samsung suggested that it might be possible to place spyware on a phone that would keep some of its network functions active even after users pressed the power button to turn it off.

That's what I was thinking.
 

coolitic

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However, both Ericsson and Samsung suggested that it might be possible to place spyware on a phone that would keep some of its network functions active even after users pressed the power button to turn it off.

That's what I was thinking.
 

coolitic

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However, both Ericsson and Samsung suggested that it might be possible to place spyware on a phone that would keep some of its network functions active even after users pressed the power button to turn it off.

That's what I was thinking.
 

Akizu

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"what happens when you phone is off and you get a call? It says the phone is off.. so..im guessing they can "ping" your phone.. Yes? because you get back a message the subscriber can not be reached. "

No, it doesn't work that way. When you turn off your phone, it sends one last signal that tells the service provider that it has been powered-off. That's why you get different message if you powered-off the phone and different one if it went out of signal range.

As for a solution to tracking: after powering-off your cell phone just warp it in a tin foil. Yes. Tin foil. That simple.
 

onichikun

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"what happens when you phone is off and you get a call? It says the phone is off.. so..im guessing they can "ping" your phone.. Yes? because you get back a message the subscriber can not be reached. "

As Akizu mentioned your phone will broadcast a power-down message.. Even if that message isnt sent the cell towers know your last cell location.. if it can't ping it's last location and your phone is not present in a certain number of adjacent cells, your phone is deemed unreachable.

While "querying the oscillator" does indeed work due to resonant circuits, the noise you would have would prevent any unique characteristic identification solely on that -- the resonance of the RF circuit isn't going to trigger a ID broadcast to identify what oscillator you are querying.

It's more likely they have some low-powered heartbeat signal that continues when your phone is "off". To fix it just wrap it in tinfoil, or any conductive cage... the NSA can't beat physics.... hopefully :3
 

Onus

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This kind of thing is why, in secure environments, cell phones are either simply not allowed, or must have their batteries removed.
 
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