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

11–20 of 85 posts

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

#11

Post by gnicholas »

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

FWIW, this can be capability can be disabled when you power down the device. Not sure if you can make it a persistent preference or if you have to do it every time, though.

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

#12

Post by sieabah »

Was this not apparent when every manufacturer was working on Covid tracking in the open? Were people really not aware of the technologies being employed? That technology now exists on every phone that has had any semblance of an update in the past two years. There is no privacy, you have always been and will always be completely trackable.

You can even use ultrasonic sound signatures so your phone doesn't even need to be broadcasting using bluetooth, wifi, or cell. Just the speaker alone at a pitch you cannot hear is enough to track you.

Edit: I enjoy how this gets downvoted for pointing out that technology has downsides...

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

#13

Post by lancesells »

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

That's a setting you can turn off in iOS

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

#15

Post by DINKDINK »

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 and I/Q imbalance.

links to the paper:

https://cseweb.ucsd.edu/~nibhaska/papers/sp22_paper.pdf

https://www.researchgate.net/publication/360655420_Evaluatin...

Git repo: https://github.com/ucsdsysnet/blephytracking

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

#16

Post by barbegal »

mvelie wrote: post #3

Apple has added recently at least for the BTLE implementation an address randomization much like they did for wifi, details of which can be found here: https://support.apple.com/guide/security/bluetooth-security-...

Address randomization helps but it's not enough. The phone still transmits at a regular cadence so it's pretty easy to figure out which old address has changed into which new address and keep tracking the same device.

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

#19

Post by hinkley »

giuliomagnifico wrote: post #4
mvelie wrote: post #3

Apple has added recently at least for the BTLE implementation an address randomization much like they did for wifi, details of which can be found here: https://support.apple.com/guide/security/bluetooth-security-...

> All wireless devices have small manufacturing imperfections in the hardware that are unique to each device. These fingerprints are an accidental byproduct of the manufacturing process. These imperfections in Bluetooth hardware result in unique distortions, which can be used as a fingerprint to track a specific device. >For Bluetooth, this would allow an attacker to circumvent anti-tracking techniques such as consta…

It's like sci fi movies where they track ships based on their engines. Turn off your transponder and they still know who you are, unless you really try to camouflage yourself.

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

#20

Post by cvccvroomvroom »

This is generally old news.

Philz Coffee in Palo Alto, CA and major department stores in the US have been doing this for years to track foot traffic. If you don't want to be tracked, turn off BT and Wifi and demand the protocol stds body and mfgrs support even stronger randomized hw addresses.

Post reply on HN