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

Tracking a cellphone is easy, especially for the National Security Agency. But can you track a cellphone that's been turned off?

It sounds impossible, but the NSA apparently has been able to track powered-down mobile phones since 2004, as reported by The Washington Post in July 2013.

The Post's mention of this ability was brief. It was buried within a longer narrative regarding the NSA's partnership with the U.S. military's Joint Special Operations Command (JSOC) to track and kill high-profile al-Qaida targets in Iraq:

"By September 2004, a new NSA technique enabled the agency to find cellphones even when they were turned off. JSOC troops called this 'The Find,' and it gave them thousands of new targets," the Post reported.

MORE: NSA Leaks 2013 – A Timeline of NSA Revelations

Hoping for more information, British watchdog group Privacy International in August wrote directly to eight major mobile-phone manufacturers and operating-system providers asking how that could be possible.

So far, Ericsson, Google, Nokia and Samsung have responded — and, as far as they know or can say, it shouldn't be possible to track powered-down cellphones.

All four companies claimed to be unaware of any exploit or vulnerability that would make tracking a powered-down phone possible, since pressing the "off" button on a phone entirely deactivates its network connectivity.

"When a mobile device running the Android Operating System is powered off, there is no part of the Operating System that remains on or emits a signal," Google told Privacy International.

Similarly, Samsung Vice President Hyunjoon Kim wrote: "Without the [mobile phone's] power source, it is not possible to transmit any signal, due to the components being inactive. Thus the powered-off devices are not able to be tracked or monitored by any 3rd party." (You can read Samsung's letter on Privacy International's website.)

Nokia's Chad Fentress had a similar statement, but his phrasing raised eyebrows at Privacy International: "Our devices are designed so that when they are switched off, the radio transceivers within the devices should be powered off." (Nokia's statement is also available on the website.)

Privacy International research officer Richard Tynan told Ars Technica that Nokia's wording, particularly the "should," is suspicious.

"Nokia's wording is very nuanced," Tynan said. "They don't say that transceivers 'are' switched off."

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.

Without confirmation from the NSA, or access to the documents leaked by former NSA contractor Edward Snowden, it's impossible to tell exactly how, or even if, tracking powered-down mobile phones is possible.

Privacy International is still waiting for responses from Apple, HTC, Microsoft and BlackBerry. The organization plans to reach out to LG, Motorola, Sony and others in the near future.

Email jscharr@techmedianetwork.com or follow her @JillScharr and Google+.  Follow us @TomsGuide, on Facebook and on Google+.

Jill Scharr is a creative writer and narrative designer in the videogame industry. She's currently Project Lead Writer at the games studio Harebrained Schemes, and has also worked at Bungie. Prior to that she worked as a Staff Writer for Tom's Guide, covering video games, online security, 3D printing and tech innovation among many subjects. 

  • gggplaya
    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.
  • ocilfa
    @gggplaya That's why you remove the battery.
  • InvalidError
    "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
    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
    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
    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.

  • razor512
    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
    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.
  • burmese_dude
    NSA has the all knowing Miss Cleo. She can tell everything in fake Jamaican accent.
  • das_stig
    How about the cpu itself running internal code to access the radio ??