Can mobile phones be tracked when they're switched off?

Hhorde · 28 Jan

https://boingboing.net/2025/01/28/nsa-can-track-powered-down-phones-how-to-actually-protect-your-privacy.html (archive link)

Just want to let you know your cell phone is tracking you regardless if you have it in airplane mode or not. It even ping's when it's turned off. There is only one way to know for sure that you are not being tracked. That's to keep all signals from coming out or going into your devices.

Some relevant issue(s) on GrapheneOS.

Can someone elaborate on whether leaving your device shutdown it contacts cell towers? There are some interesting discussions here https://news.ycombinator.com/item?id=42855678

I think the current approach to protect against it is having the phone always in faraday bag when not in use, and GrapheneOS implement the Airplane-On always mode, enable that feature.

Note: for initial GrapheneOS installation setup on Pixel with stock OS, you will leak some identifiers to cell towers and to google when you enable Wi-Fi for OEM unlocking if your device model is variants (SKUs) which support being sold as locked devices by carriers or when you want to follow GrapheneOS's "best practices" by connecting to Wi-Fi and update stock OS before flashing GrapheneOS.

It's best practice to update the device before installing GrapheneOS to have the latest firmware for connecting the device to the computer and performing the early flashing process. Either way, GrapheneOS flashes the latest firmware early in the installation process.

raccoondad · 28 Jan

horde "device model is variants (SKUs) which support being sold as locked devices by carriers"

I bought my device directly from the Google store (store.google.com) and had to connect it to a network to do OEM unlocking, from what I remember. Was an unlocked model

Dde0u · 28 Jan

horde It is possible to track a phone that is pretending to be off if malware to pretend to be off has been installed on that individual phone.

https://skeptics.stackexchange.com/questions/17053/can-mobile-phones-be-tracked-when-theyre-switched-off

faxe · 28 Jan

From the article:

Today, Randy Zar, CEO of Faraday pouch manufacturer SLNT wrote:

so obviously he will recommend buying a Faraday pouch, while GrapheneOS FAQ states:

Airplane mode is the only way to avoid the cellular network tracking your device and works correctly on the devices we support.

also GrapheneOS account here often stated that Airplane mode fully turns off all radios (it's surely also somewhere in their docs).

Besides that this slate article states, that phones first have to be infected with malware for the tracking you mentioned (NSA "The Finder") to work.

Dde0u · 28 Jan

horde Can someone elaborate on whether leaving your device shutdown it contacts cell towers?

Can people who disbelieve the project's statement on this matter please avoid amplifying low-quality alarmist drivel and instead hire somebody with RF test equipment?

DDeletedUser127 · 28 Jan

de0u you are not my friend but I consider you my friend whether you like it or not :)

BBlastoidea · 28 Jan

Wrap both your phone and your head tightly in heavy-duty aluminum foil.

Make sure the openings for your eyes are less than a tenth of a wavelength across.

KKitsuneNoBaka · 29 Jan

I'm working in mountain shelter. I have contact with mountain rescuer's. They have device given from police that emulates cell tower. If they know IMEI (by giving phone number to police) they can activate powered off phone and track it to search for people in mountains.

DDeletedUser127 · 29 Jan

KitsuneNoBaka BS. They only look at your location history linked to phone's Google account if available. That would be my best guess.

phone-company · 29 Jan

KitsuneNoBaka known as "imsi catcher" for example by Rhode und Schwarz

GrapheneOS · 29 Jan

KitsuneNoBaka This is a completely false claim. You seem to be confusing the phone being asleep with off.

GrapheneOS · 29 Jan

phone-company It's a false claim, there is nothing that does it.

Dde0u · 29 Jan

KitsuneNoBaka I'm working in mountain shelter. I have contact with mountain rescuer's. They have device given from police that emulates cell tower. If they know IMEI (by giving phone number to police) they can activate powered off phone and track it to search for people in mountains.

What happens if you write your IMEI on a piece of paper, turn your phone off, hide your phone, come back, give them the paper, and watch them activate their device? Can they track your phone? I expect not.

KKitsuneNoBaka · 30 Jan

As long as it's connected to battery, battery have power and radio waves aren't blocked then they can connect and activate phone. They have it on helicopter so they make circles to pinpoint location to few hundreds meters. If phone connects to other towers then it's more accurate.
It's better than to search 100 square kilometers of mountain blindly.

KKitsuneNoBaka · 30 Jan

And you can't give them imei and ask for search. It must be accepted by police and prosecutor.

phone-company · 30 Jan

GrapheneOS whatvis false? Few years ago we are Wirkung with that stuff. It's worked 100%. So what do you mean?
Imsi Catchers were deployed by the authorities. They simulated a radio cell to the end device. The mobile device logged into this fake cell and decryption took place. This no longer works today.

KKitsuneNoBaka · 30 Jan

GrapheneOS nowadays there is no phone completely off. Dunno about Pixels phones but this imei activation system was introduced 2 years ago and was used 3 times with dead tourists.
Dunno if they had phones off, but rescuer's said that doesn't matter.

Dde0u · 30 Jan

KitsuneNoBaka As long as it's connected to battery, battery have power and radio waves aren't blocked then they can connect and activate phone.

Extraordinary claims require extraordinary evidence. Stating the claim again is not evidence.

Aside from experimenting, perhaps you can provide specific information about which equipment is used, such as a model number, and perhaps there would be documentation about whether or not the device can remotely power devices on.

Dde0u · 30 Jan

KitsuneNoBaka Dunno if they had phones off, but rescuer's said that doesn't matter.

Nobody doubts that phones that are on can be located. The extraordinary claim here is the one about phones that are off. For it to be relevant here, it would need to be true of Google Pixel phones in particular.

It would be good to provide actual evidence of some sort, as opposed to unsourced rumor.