Bluetooth already broadcasts and has a UID, I have used this a few times in books as plot-outline to identify an antagonist, and I now wonder if NFC has a similar UID It would be interesting to decode the data and see.
NFC however isn't touched by the airplane mode
...At least it was like that on the android phones I owned
On the Pixel 7, Airplane mode absolutely did not disable those frequency spikes upon screen unlock. Only disabling NFC through the dedicated setting in the phone’s parameters did (Settings > Connected devices > Connection Preferences > NFC). This theoretically puts Android users at greater risk, since on iOS, Airplane mode does disable those polling signals.
It’s easy to see how an average user might assume they’ve gone completely dark by enabling Airplane mode on an Android device—when in fact, they haven’t.
I’ll update the original post with this information, and thank you for pointing it out.
Can be harmful even without identifying information in situations where it's enough to decide if some building is occupied or not.
Bluetooth LE does explicitly broadcast its MAC address in some modes, but offers various forms of private or random address modes to mitigate the problem.
https://www.theregister.com/2021/10/22/bluetooth_tracking_de...
https://cec.gmu.edu/news/2025-02/find-my-hacker-how-apples-n...
The Trojan code runs on the computer to be tracked.
It retrieves the advertising address, acquires the matching
public key from our server, and then advertises lost messages
The first one describes radio fingerprinting, which is relatively new, concerning, and might be tricky to address.
See https://inria.hal.science/hal-02394629v1 for the theoretical bases then hop to https://samteplov.com/uploads/shmoocon20/slides.pdf for an example applying to Apple devices
Those who said the randomization and other techniques were sufficient were wrong: https://petsymposium.org/popets/2020/popets-2020-0003.pdf will show you how they changed their mind :)
It's not just apple: google nearby has also been reversed: https://publications.cispa.saarland/2748/ and https://www.ndss-symposium.org/wp-content/uploads/2019/02/nd... talks about attacks, but there's no need for that: just find identifiers that let you link the addresses
Even if you don't have any identifiers, the Bluetooth address randomization happens only about every 15 minutes: the manufacturer specific data in the public advertisement (or even the frequency and the length of these advertisements) during these 15 minutes periods can be used for linking the randomized addresses
In other words, you could possibly track a given device through an area with enough sensors, e.g. a store, but not across visits.
The "randomization" seems to be a pseudo-randomization: with the seed and the timestamp, you should be able to deduce the future "randomized" addresses.
Ex: blocking 3rd party cookies always now. Breaks countless websites which I need to work reliably. “Manage unused website/app’s permissions” even after I specifically granted them! Randomized virtual credit card numbers in Wallet: for no good reason, you thoroughly fucked up a refund attempt for me, >$500! And randomized MAC addresses by default for EVERY. SINGLE. SSID. It’s unhinged. It’s fake protection.
As a matter of fact, I do not enjoy my devices lying to my ISP, or to my college campus, my medical clinic, or to my employers. Device, please identify yourself without wearing a fuckin’ Groucho mask on top, and put on your big boy pants.
Google calls it “my privacy” but it’s not their business model to keep my stuff private to me but to Google and their partners.
Google is trying to keep their own secrets like what their hardware MAC address really is, (because Google themselves are tracking everyone’s radio-enabled devices in every public space with far more sophisticated methods)
or hide/virtualize my credit card details, and protecting the card from crackers who wear hoodies, build EBM playlists, and use Firefox? that is a side-effect at best, especially considering how they are already a crazy non-bank middleman 3rd party with a miasma of shifting TOS and hundreds of advertising partners salivating to know what you paid for 3 milliseconds ago. Sheesh.