Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Bluetooth signals can be used to identify and track smartphones

ucsdnews.ucsd.edu

Post reply on HN
Print view View original

31–40 of 85 posts

Re: Bluetooth signals can be used to identify and track smartphones

#31

Post by nonameiguess »

lxgr wrote: post #8

> “As far as we know, the only thing that definitely stops Bluetooth beacons is turning off your phone,” Bhaskar said. At least for recent Apple devices, that's not true anymore (intentionally, as it is used to support "Find my iPhone" even with a dead battery or on a phone that's been switched off): https://arxiv.org/abs/2205.06114

I just looked it up and apparently this feature continues to work even in airplane mode. That seems crazy to me that doing that is even legal. What good is airplane mode if it doesn't actually disable all onboard radios? I get that it's theater and mobile device radios don't really interfere with airplane takeoff and landing anyway, but given the rule still exists, why are all iPhone owners allowed to ignore it because their devices don't support turning off the radios?

Re: Bluetooth signals can be used to identify and track smartphones

#32

Post by femto »

DINKDINK wrote: post #15

comments are focusing on the protocol's message content which is not the source of the ability to track broadcasters. The ability comes from detecting nuances in the RF signal: >BLE [snip] imperfections are introduced by the shared I/Q frontend of the chipset (Figure 1). They result in two measurable metrics in BLE and WiFi transmissions: Carrier Frequency Offset (CFO) and I/Q imperfections, specifically: I/Q offset…

Section IV of the paper, "Challenges", is interesting reading. As expected CFO displays a strong temperature dependence, causing wrong identifications. Further, I/Q characteristics tend to be close for a given chipset, so I/Q imperfections are more or less identifying the chipset. It's easy to detect different models of phone, but harder to detect individual phones. It doesn't strike me as a serious threat (yet).

A fun exercise would be to synthesise the detection of all phones in the area. By monitoring CFO over a period of time for lots of phones distributed over an area, maybe it would be possible to build a temperature profile of the area under surveillance and compensate the CFO measurements for temperature. Whilst crystals do drift with temperature, the frequency of a given crystal is highly repeatable as a function of temperature.

Re: Bluetooth signals can be used to identify and track smartphones

#34

Post by jtaft »

walterbell wrote: post #25

Do Apple security updates include firmware for the radio basebands? If a radio baseband has been compromised, how can it be restored to a known-good state, e.g. would iOS reinstallation via Apple Configurator also restore the baseband firmware?

It appears so? https://support.apple.com/en-om/HT212814 mention baseband.

Re: Bluetooth signals can be used to identify and track smartphones

#35

Post by judge2020 »

walterbell wrote: post #30
pmoriarty wrote: post #27

In another hundred years are people going to look back at this time as a barbaric age of surveillance or are they going to be even more surveilled and controlled than ever before? So far the trend is towards the latter...

Coming in 2024: Device-Free Wireless Sensing (DFWS), aka Wi-Fi 7 Sensing that can "see through" home/business walls.

I think you mistyped 2015 https://youtu.be/fGZzNZnYIHo

Re: Bluetooth signals can be used to identify and track smartphones

#36

Post by _carbyau_ »

neuralRiot wrote: post #9
lxgr wrote: post #8

> “As far as we know, the only thing that definitely stops Bluetooth beacons is turning off your phone,” Bhaskar said. At least for recent Apple devices, that's not true anymore (intentionally, as it is used to support "Find my iPhone" even with a dead battery or on a phone that's been switched off): https://arxiv.org/abs/2205.06114

Faraday bags

Fortunately, convenient and cheap with tasty contents!

https://arstechnica.com/information-technology/2017/11/austr...

Re: Bluetooth signals can be used to identify and track smartphones

#37

Post by KennyBlanken »

nonameiguess wrote: post #31
lxgr wrote: post #8

> “As far as we know, the only thing that definitely stops Bluetooth beacons is turning off your phone,” Bhaskar said. At least for recent Apple devices, that's not true anymore (intentionally, as it is used to support "Find my iPhone" even with a dead battery or on a phone that's been switched off): https://arxiv.org/abs/2205.06114

I just looked it up and apparently this feature continues to work even in airplane mode. That seems crazy to me that doing that is even legal. What good is airplane mode if it doesn't actually disable all onboard radios? I get that it's theater and mobile device radios don't really interfere with airplane takeoff and landing anyway, but given the rule still exists, why are all iPhone owners allowed to ignore it becau…

In Android turning "off" bluetooth and wifi just puts them in listen-only mode and this has been true for a long, long time.

Zebra devices have always-on bluetooth beacon capability, and even a second bluetooth radio in the battery(!): https://techdocs.zebra.com/emdk-for-android/9-1/mx/beaconmgr...

Re: Bluetooth signals can be used to identify and track smartphones

#38

Post by lxgr »

nonameiguess wrote: post #31
lxgr wrote: post #8

> “As far as we know, the only thing that definitely stops Bluetooth beacons is turning off your phone,” Bhaskar said. At least for recent Apple devices, that's not true anymore (intentionally, as it is used to support "Find my iPhone" even with a dead battery or on a phone that's been switched off): https://arxiv.org/abs/2205.06114

I just looked it up and apparently this feature continues to work even in airplane mode. That seems crazy to me that doing that is even legal. What good is airplane mode if it doesn't actually disable all onboard radios? I get that it's theater and mobile device radios don't really interfere with airplane takeoff and landing anyway, but given the rule still exists, why are all iPhone owners allowed to ignore it becau…

Where did you find confirmation that "Find my" still broadcasts in airplane mode?

Re: Bluetooth signals can be used to identify and track smartphones

#39

Post by walterbell »

judge2020 wrote: post #35
walterbell wrote: post #30

Earlier quoted context omitted.

Coming in 2024: Device-Free Wireless Sensing (DFWS), aka Wi-Fi 7 Sensing that can "see through" home/business walls.

I think you mistyped 2015 https://youtu.be/fGZzNZnYIHo

DFWS has indeed existed for some time, but 802.11bf in 2024 would standardize mass deployment in new consumer and business routers.
Post reply on HN