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Some Android apps are using ultrasonic beacons to track users

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Re: Some Android apps are using ultrasonic beacons to track users

#51

Post by ceejayoz »

hackuser wrote: post #50
Yetanfou wrote: post #35

Earlier quoted context omitted.

They'd do it to connect profiles between the TV (which knows what you're watching) and any mobile devices within ultrasound reach (i.e. line of sight) of the TV. Do this a few times and it quickly becomes clear which phone is usually within range of the TV, and with that the profiles can be merged, giving a broader view of the user behind these devices. The solution is simple: don't get a 'smart' television. Better s…

> don't get a 'smart' television Will that prevent ultrasonic beacons? I assumed the speakers were the same on smart and 'dumb' TVs.

The smart televisions are far more likely to have code (or be updated with code) that can be used to emit unique tracking signals of some sort.

Re: Some Android apps are using ultrasonic beacons to track users

#52

Post by hackuser »

ceejayoz wrote: post #51
hackuser wrote: post #50

Earlier quoted context omitted.

> don't get a 'smart' television Will that prevent ultrasonic beacons? I assumed the speakers were the same on smart and 'dumb' TVs.

The smart televisions are far more likely to have code (or be updated with code) that can be used to emit unique tracking signals of some sort.

Sorry if I'm missing something, but television programming usually doesn't require code in the TV in order to emit audio. Is audio in ultrasonic frequencies a special case?

Re: Some Android apps are using ultrasonic beacons to track users

#53

Post by hackuser »

mdekkers wrote: post #9

It is these kind of "behind your back" shenanigans that will quickly force governments to move to regulating the industry, giving rise to a whinging chorus of "leave us alone" from the industry. An industry that has shown itself to be utterly untrustworthy, sneaky and aggressively invasive. I see a need for a good, simple, slick and solid interface that allows you to select what functions an app can and cannot do on…

> these kind of "behind your back" shenanigans that will quickly force governments to move to regulating the industry

These kinds of things have been going on for years, and yet the U.S. government, for one, just reduced privacy protections for consumers.

Re: Some Android apps are using ultrasonic beacons to track users

#55

Post by tanvach »

You don't necessary need ultrasound, but a modulation scheme to put the sound energy outside of hearing range. Ultrasound can be unreliable since phones have different frequency response that affects sensitivity. Also compression tends to apply low pass filter, so overall the range is quite variable.

To combat this, you can add forward error correction code, and have the audio source transmit data at low bit rate. Also, it's possible to modulate data using spread spectrum sequence (similar to GPS and ultrawideband) to reduce the energy below hearing threshold.

The state of the art is not to embed data at all, but use audio fingerprinting, aka Shazam.

Re: Some Android apps are using ultrasonic beacons to track users

#56

Post by obsurveyor »

dtech wrote: post #25
strmpnk wrote: post #18

Earlier quoted context omitted.

That model is backwards. If there is one thing iOS got right, it's the permission prompt. Nobody reads those lists and it's hard to know what the intent is without context in the app. Having the app ask on first use makes much more sense. It's much less likely to get away with this. Even better, you can still use the app if you say no. It will just get dummy values back.

This works the same since Android 6 (2015)

Google doesn't even apply the permissions very tightly. App makers are happy to ignore recommendations(I don't think they're requirements) to work, even if not granted the permission. They just do things like prompt over and over or completely stop working if they detect they're given the fake, default data from not being given permission to things like your Contacts or Location. There's no user agency in Android 6.0+ permissions really, the apps can just hold their functionality over the users' head until they accede.

Also, Android permissions are strange. Like, why does an app need access to Contacts to use my Google Account to sign in? An account is not a contact and just because I want to let you unify my logins, that doesn't mean I want you to have access to my contacts.

Re: Some Android apps are using ultrasonic beacons to track users

#57

Post by URSpider94 »

posterboy wrote: post #21
ungzd wrote: post #3

Is it really ultrasound? Microphones on phones may be able to pick this but what speakers are able to play even 20 kHz? And these apps should always listen, that will drain battery quickly, so these apps will be listed in top power-consuming apps and user will notice it.

your first point coupled with diminishing free air range in bands above 40kHz makes this hack seem like a futile attempt to simply gather as much data as possible, as low or uncorrelated as it might be. Some phones might be more cappable than others, however, and air is dense enough for several meters of significant ultrasound transmission at low power. With e.g. Samsung TVs always listening, I wouldn't be surprised…

I don't think people are using true ultrasound, e.g. 40kHz. In most cases, it's more like "poor man's ultrasound" at 19 kHz, Just outside the hearing range of most people. They have to stay as close as possible to the human hearing range to avoid audio low-pass filters and simple capability envelope of the speakers and microphones.

Re: Some Android apps are using ultrasonic beacons to track users

#58

Post by cazum »

hackuser wrote: post #52
ceejayoz wrote: post #51

Earlier quoted context omitted.

The smart televisions are far more likely to have code (or be updated with code) that can be used to emit unique tracking signals of some sort.

Sorry if I'm missing something, but television programming usually doesn't require code in the TV in order to emit audio. Is audio in ultrasonic frequencies a special case?

Although I can't confirm this myself, a few people here have mentioned that its likely that a digital TV signal's audio track would be compressed to remove inaudible ranges. This would require that any ultrasonic data be added by the TV.

Re: Some Android apps are using ultrasonic beacons to track users

#59

Post by wodenokoto »

hackuser wrote: post #52
ceejayoz wrote: post #51

Earlier quoted context omitted.

The smart televisions are far more likely to have code (or be updated with code) that can be used to emit unique tracking signals of some sort.

Sorry if I'm missing something, but television programming usually doesn't require code in the TV in order to emit audio. Is audio in ultrasonic frequencies a special case?

AFAICT Yatenfou is saying that the ultrasonic tracking beacon is done by software on the smart TV and not actually part of the television signal.

Re: Some Android apps are using ultrasonic beacons to track users

#60

Post by semi-extrinsic »

cazum wrote: post #58
hackuser wrote: post #52

Earlier quoted context omitted.

Sorry if I'm missing something, but television programming usually doesn't require code in the TV in order to emit audio. Is audio in ultrasonic frequencies a special case?

Although I can't confirm this myself, a few people here have mentioned that its likely that a digital TV signal's audio track would be compressed to remove inaudible ranges. This would require that any ultrasonic data be added by the TV.

From what I can tell, HDTV audio is typically sampled at 48kHz and compressed with AAC using spectral band replication (SBR) techniques. I'd definitely say it's plausible that signal could contain stuff outside a normal adult's hearing range.
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