[HN Gopher] iPhone apps can tell many things about you through t...
___________________________________________________________________
iPhone apps can tell many things about you through the
accelerometer
Author : giuliomagnifico
Score : 341 points
Date : 2021-11-08 09:49 UTC (13 hours ago)
(HTM) web link (www.mysk.blog)
(TXT) w3m dump (www.mysk.blog)
| RubberShoes wrote:
| I have always suspected this and curious what TikTok is reading.
| For example, if I put my phone down and the video showing
| continues to loop, does TikTok's algo ignore my 'time watching'
| because it is aware my phone is on a surface vs in my hand.
| wyuenho wrote:
| Is this why the M1 Pro/Max MBPs also come with an accelerometer
| and gyroscope [1] even if it doesn't come with mechanical hard
| drives? Because Apple needs to support Catalyst apps?
|
| [1]:
| https://www.ifixit.com/Guide/MacBook+Pro+14-Inch+2021+Chip+I...
| Sandvich wrote:
| I would venture that this has more to do with Universal
| Control. Perhaps they use the orientation data to help with
| some heuristics?
| itake wrote:
| Companies also use accelerometer data to know if the phone is
| running in a simulator.
| gnu8 wrote:
| That suggests a cool little project to build a module that
| fakes the output of an accelerometer without being obviously
| fake.
| a9h74j wrote:
| Relevant systematic review: accelerometers and privacy[1]
|
| [1] https://dl.acm.org/doi/pdf/10.1145/3309074.3309076
| makeitagoood wrote:
| There are Android OSes like GrapheneOS with sensors permission so
| that apps won't have access to them unless you grant them access.
| rconti wrote:
| Not super related, but my Physical Therapist was super impressed
| that my phone could show my left/right imbalance ("walking
| asymmetry" in iOS health).
|
| It's been a pretty good measure of my progress in recovery post-
| surgery. She had no idea this even existed, and then had a second
| patient point it out to her just a week or two later. I imagine
| Android has similar features (or 3rd party apps can be installed
| to do so).
| wongarsu wrote:
| So for context I looked at the papers behind the scenarios.
|
| - The heart rate sensing is done on a smart watch, not a phone,
| and needs data from the actual heart rate sensor every couple of
| days [1].
|
| - The breathing rate is determined from a phone put on the breast
| or the abdomen [2]. Not really a threat vector in that form.
|
| - The audio stuff is incredibly impressive [3], but it doesn't
| look like they can reconstruct text with meaningful reliability,
| it's more about identifying the person or at least the gender of
| the person on the other end of the line.
|
| The location and activity detection scenarios seem the most
| credible to me, but the for targeted attacks the audio
| reconstruction might also work. The other two don't really seem
| credible to me yet, but good to be aware of them.
|
| 1: https://arxiv.org/pdf/1807.04667.pdf
|
| 2: http://www.ijetch.org/vol8/900-M302.pdf
|
| 3: https://arxiv.org/pdf/1907.05972.pdf
| whoisjuan wrote:
| Future Interfaces Group at CMU has done a lot of interesting
| research where they can infer a large amount of enviromental
| context just from accelerometer/gyroscope alone.
| http://www.figlab.com/
|
| Some examples:
|
| https://www.youtube.com/watch?v=a-ImMjOrbbI
|
| https://www.youtube.com/watch?v=gCA-0cPS1eM
|
| They also have a bunch of research using other sensors in the
| phone as an input.
| KermitTheFrog wrote:
| Using the accelerometer/gyro data, you can also guess the
| password from the device with quite good accuracy(it depend) if
| you type in your hand and not on a flat surface.
| djrogers wrote:
| No you can't - apps can't read Core Motion data when your
| screen is locked, or they're in the background.
| KermitTheFrog wrote:
| You may create App such as a (kind of)"navigation" app. But
| I'm not sure about collection data while screen is locked
| and password is required. Need to play with it.
| elliekelly wrote:
| I would guess the _vast_ majority of people who need to set
| a PIN for the CVS app or their banking app or whatever use
| the same PIN to unlock their phone.
| mdasen wrote:
| If they're creating a PIN in the app, the developer could
| just store that in plain text more easily than trying to
| derive it from the accelerometer. I think you're right
| that most people probably use the same PIN for their
| phone and apps, but then the app maker has easy access to
| the PIN because the user gave it to them
| alecr95 wrote:
| I don't have an iPhone, but does it have overlays for
| things like password managers?
|
| Android definitely does, and I assume the same research
| around guessing text input would apply.
| wlesieutre wrote:
| It does, but I unlock it with FaceID rather than a
| password. Cameras recording me typing my bitwarden master
| password are a bigger security concern for my password
| security already.
| walterbell wrote:
| Wish there was an option to disable the magnified, per-
| key, onscreen keyboard bubbles when entering a password.
| Provide an option to show the password on entry or not,
| same as desktop input fields for passwords. But don't
| magnify each character and invert the screen to make it
| easier for camera imaging.
| rootusrootus wrote:
| There is, at least on iPhones. But it is for all keyboard
| input, not just passwords. Go to Settings -> General ->
| Keyboard, toggle Character Preview to off.
| walterbell wrote:
| Thanks, that's helpful, although the iOS lock screen
| appears to be excluded.
| mimsee wrote:
| Is there an application on iOS that can listen for the
| accelerometer/gyro data on the background?
| eyelidlessness wrote:
| Health definitely does (and likely needs to for much of its
| functionality), but it's first party so you've pretty much
| already trusted the vendor with that data.
| janekm wrote:
| For what it's worth I did a fair bit of research on using
| accelerometers for heart rate and respiratory rate
| determination
| (https://ieeexplore.ieee.org/abstract/document/5504743) and
| while placement on the abdomen/chest is preferable, if the
| subject has a high excursion and low adipose tissue I was in
| some instances able to get a good signal from a device worn in
| a trouser or jacket pocket (especially when sitting). Never
| published that because it wasn't useful in a medical setting
| but could be of interest if you're recording it
| opportunistically.
| lazyjeff wrote:
| One of my pet peeves is that these articles never report the a
| priori distribution of labels that are being predicted.
| Guessing whether you're at sitting vs walking with 90% accuracy
| is not very useful if most people are usually sitting.
| Actually, the article here doesn't even report the accuracy:
| neither the stdev error for scalar predictions, or the
| precision/recall and number of classes predicted for ordinal
| data. Actual results would go a long way to making the article
| meaningful.
|
| There's a growing number of these "computers can now
| predict..." articles, like "one email from you can tell your
| mood" or "your choice of snap filter reveals your age."
| Basically, in practice anything can predict anything, usually
| slightly better than random, so there's an infinite number of
| articles to write that sound shocking. If I had a bit of
| training data, I can easily write a script to predict everyone
| here's salary based on their comments using bag-of-words, and I
| bet I can do better than random guessing.
| aaaaaaaaaaab wrote:
| >Facebook reads the accelerometer all the time. Facebook actually
| shows a support prompt if a shake event is detected across the
| app. This could be one reason why Facebook reads accelerometer
| data.
|
| No. Shake gestures are handled at the OS level and you only get
| began/changed/ended callbacks. Raw accelerometer data requires
| the CoreMotion framework, and it's a lower level API. They are
| definitely using it for something else.
|
| This is also confirmed by this:
|
| >The prompt has an option to switch this feature off. However,
| switching it off doesn't stop the app from reading the
| accelerometer.
| dilippkumar wrote:
| I've heard unreliable and whispered rumors (from the tech
| grapevine) that the accelerometer was a bot-farm mitigation
| strategy.
|
| The idea is that a bot farm with thousands of phones on racks
| won't have some signature that the accelerometer should see
| when the screen is tapped (for example, when typing a message
| or hitting a like button).
|
| I happen to believe this theory.
| nimih wrote:
| It's probably being used for multiple purposes, regardless of
| the original intent. Recall that FB originally collected
| phone numbers for 2FA, but years later decided to use the
| information for ad targeting[1]. Not that Facebook is unique
| in this regard, of course; my own experience at companies
| which collect various bits and pieces of customer data is
| that, once the data is in a database somewhere, people are
| pretty good at finding excuses to use it.
|
| [1] https://www.impactplus.com/blog/facebooks-using-2fa-
| phone-nu...
| RandallBrown wrote:
| It's been a few years but I do recall adding a framework that
| claimed to use the accelerometer to help with bot detection.
| I believe it was PerimeterX.
| jbverschoor wrote:
| Well it's handy to know if your phone is being held, in the
| car, on your desk.
|
| You can 'track' if someone glanced at notifications, doing a
| spaced-repetition type delay between glances.
|
| Or maybe you want notification when you're looking at your
| phone (certain angle and shakeyness). Or maybe when you're on
| the phone (different angle).
| RicoElectrico wrote:
| > They are definitely using it for something else.
|
| Like 3D and 360 photos.
| jonplackett wrote:
| If they were really only using it for this, it would only
| activate when viewing them.
|
| It's good practice to only activate the accelerometer when in
| use because it uses up battery.
| jtbayly wrote:
| It uses essentially no battery. IIRC, it uses so little
| that even when your phone battery runs out and the phone
| turns off, the accelerometer keeps counting your steps.
| skohan wrote:
| But constantly recording it and phoning home might be
| using significant battery
| spicybright wrote:
| Meh, not if you store everything then bulk send it later.
| InitialLastName wrote:
| If apps were worried that phoning home with the data they
| recorded used significant battery, we might be in a
| different position in terms of how frequently they do it.
| chrisshroba wrote:
| Wow really? Do you have a source on that?
| magicalhippo wrote:
| Several such "motion chips" have onboard motion
| processing. As a random example the MPU-9250[1], a 9-DOF
| IMU, has a low-power pedometer feature which can keep
| step count while host processor sleeps or is offline.
|
| [1]: https://product.tdk.com/en/search/sensor/mortion-
| inertial/im...
| floatboth wrote:
| Even without onboard processing it's a very obvious move
| to offload it to a tiny microcontroller. Apple actually
| started by using a physically separate NXP micro that
| they branded "M7". Now it is of course on the main chip,
| but still a separate Cortex-M core.
| jtbayly wrote:
| This is old. Could have changed since then, but here you
| go: https://www.dailymail.co.uk/sciencetech/article-25737
| 61/amp/...
| Nextgrid wrote:
| Step counting may be implemented in hardware so the main
| CPU doesn't have to continuously stream & process the
| accelerometer's data.
| nawgz wrote:
| I doubt it, it's clearly batched & a bit lazy
| iudqnolq wrote:
| Isn't that exactly what you would see if there was
| separate hardware that recorded steps, and the main
| hardware polled it occasionally.
| setpatchaddress wrote:
| Even if accelerometer data is free, IPC'ing the data to
| the app consumes a small amount of power. It adds up over
| time. If it's not needed, the app shouldn't subscribe to
| it.
| hbn wrote:
| It can't be that intensive considering Apple's done that
| parallax homescreen effect since like iOS7. Also when
| you're in the Safari tab overview, it reads the gyroscope
| to do a 3D effect where the tabs tilt forwards/backwards.
| Probably a few other areas I'm not thinking of too.
| thrwyoilarticle wrote:
| The Facebook apps and websites are full of bugs, bad code,
| bad practices.
| moffkalast wrote:
| You'd need the gyro for that, more like.
| ChicagoBoy11 wrote:
| Does anyone have any examples of this stuff working out in the
| real world? Particularly curious about the "we used accelerometer
| data" part of it to infer that these two individuals were in the
| same place.
| mcherm wrote:
| For comparison, how are the controls on access to accelerometer
| data on Android?
| makeitagoood wrote:
| GrapheneOS has a Sensors permission toggle to allow/disallow an
| app accessing sensors.
| meibo wrote:
| The APIs are not restricted, but are now rate-limited to make
| inference of information like this very hard.
|
| https://developer.android.com/guide/topics/sensors/sensors_o...
| vultour wrote:
| 200Hz really isn't in the ballpark of making this "very
| hard".
| boibombeiro wrote:
| IIRC the rate was limited because someone showed it could be
| used as microphone.
| kroltan wrote:
| No permissions required to read motion data.
|
| If I remember correctly, it might be necessary to declare the
| capability in a manifest, but there's certainly no prompt, nor
| a way to opt-out of an app reading motion data in the settings.
| sp1rit wrote:
| you can "opt out" using adb by revoking the gyro permission.
| some non-google androids also have the possibility of
| revoking it with the ui, or even going as far as to promt for
| it (graphene os)
| wolpoli wrote:
| Does any one know why do web pages even have access to my
| accelerometer data without prompt?
| speedgoose wrote:
| Facebook/Meta developers have no moral, exhibit 5843352.
| durnygbur wrote:
| Do you want the stock price to grow or not? Do you want to
| maintain lion share of the ad market in the developed world or
| not?
| matheusmoreira wrote:
| > Do you want the stock price to grow or not?
|
| At the cost of privacy and peace of mind? No.
| cduzz wrote:
| You're never gonna make it to the c-suite with that
| attitude!
| durnygbur wrote:
| You'd earn enough money to even buy the adjacent real
| estate...
| rStar wrote:
| they do get profit sharing though
| rStar wrote:
| but no walls, no personal space and not a moment to
| themselves outside of a stall in the toilet. it's quite the
| hellhole.
| bryanrasmussen wrote:
| >but no walls, no desks to themselves and not a moment to
| themselves outside of a stall in the toilet.
|
| all the perks of dorm room living! I guess someone really
| wanted that feature when they were first building the
| company.
| DeathArrow wrote:
| >outside of a stall in the toilet
|
| Until they'll make toilets open space.
| spuz wrote:
| It's possible Facebook uses the accelerometer for bot detection
| or click fraud detection. They could use the data to help work
| out whether a human is interacting with the phone or a robot (do
| an image search of "click farm" if you want an idea of why this
| might work).
| hungryforcodes wrote:
| But why are people on this thread making excuses for it? I had
| no idea this was happening and certainly don't WANT this
| information to be recorded by Facebook. Do they know when I'm
| having sex if I leave the phone on my bed?
|
| And given that who ever I am with might have Facebook on her
| phone, and it might be on my bed also...
|
| That's pretty creepy.
| xanaxagoras wrote:
| > Do they know when I'm having sex if I leave the phone on my
| bed?
|
| After reading TFA it sure sounds like they do.
| marderfarker2 wrote:
| As if click farms can't spoof accelerometer already?
|
| Or skip physical hardware altogether.
| nindalf wrote:
| They do both. Mass simulators with faked sensor data as well
| as phones on racks manipulated by mechanical digits. A phone
| that never moves at all doesn't detect former but it does
| detect the latter.
| mschuster91 wrote:
| Advertising and advertising fraud are possibly the worst thing
| that has happened to privacy in general. Advertisers fight
| against privacy protection so they can shove ever better
| targeted ads for shit we don't need down our throats, and
| fraudsters force advertisers to engage middle men that resort
| to even _worse_ tactics than advertisers do just to clamp down
| a tiny bit on fraud.
|
| As for the click farms - I would not be surprised if the next
| step will be gimbal mounts that mimic an actual human's
| movement...
| notriddle wrote:
| I wonder how a Bayesian classifier would handle accelerometer
| data?
| doopy1 wrote:
| This is the #1 use in my experience. Anti-bot detection.
| Nextgrid wrote:
| It's still a breach of privacy unless it's properly disclosed
| to the user, and there's a fair question to be asked as to
| whether the bot/non-bot detection can classify _which_ "bot"
| it's looking at, and if so whether the same can be applied to
| track users.
| hyperstar wrote:
| Is the accelerometer of the iphone 5s also sensitive enough to
| pick up sound?
| DerekBickerton wrote:
| The accelerometer/gyroscope would be a great tool for spotting
| click-farms. Bunch of phones in the same location, in the same
| position, and rarely move...something shady's happening.
| mynameismon wrote:
| Could that also not be a showroom?
| spicybright wrote:
| Watch them then rock the phone board on a back massage machine
| or something.
| pie42000 wrote:
| Should be trivial to detect
| spicybright wrote:
| Should be trivial to get around tbh. You just need
| something to gently the devices.
|
| Or hell, use developer tools to simulate it.
|
| It's all an arms race, but the click farms have the
| advantage.
| kvark wrote:
| It could be a different kind of farm, like an automated testing
| farm.
| charcircuit wrote:
| If it's your automated testing farm then whitelist them. Else
| why are you letting other people's testing farm do weird
| stuff on your service?
| kingcharles wrote:
| One of the articles posted to HN recently covered this by
| talking about faking the accelerometer data to make it look
| like the phones were being randomly moved, so I guess the bot
| guys are already on top of this, from both sides of the war.
| krono wrote:
| Chrome and Edge allow access to motion sensor data by default as
| well.
|
| Edit: Both the desktop and mobile browsers.
| onion2k wrote:
| The user has to perform an action to initialise the Generic
| Sensor API, just as they do with sound. That's just a click or
| a keypress, but you can't get sensor data without it.
| krono wrote:
| I can access some basic sensor data on default Edge without
| any confirmation. All it takes is some sneaky activation
| hidden in a navlink. Motion Sensor: Allow
| (default)
| onion2k wrote:
| Sure, but that's still a user action. The point is that the
| browser can't read anything simply by the user landing on
| the page - the user has to do _something_ to enable it,
| even if they 're not aware of the consequence of that
| action. This stops most malicious usage.
| krono wrote:
| How often do you visit a website and not do anything? As
| in not even move your mouse around or scroll.
| wwarner wrote:
| How a microelectromechanical gyroscope works [0]. Contains a
| spinning disk.
|
| 0. https://www.analog.com/en/technical-articles/mems-
| gyroscope-...
| xutopia wrote:
| I wished it could tell where I am in the underground tunnel when
| the GPS doesn't have a connection.
| andylynch wrote:
| Looking at https://stackoverflow.com/questions/7829097/android-
| accelero... it seems that this could be doable - generally it
| looks like these devices are too noisy for straightforward
| inertial navigation, but constraining the problem to how far
| along your train is in a tunnel with occasional wifi is much
| more possible.
| Aachen wrote:
| Occasional WiFi? In a tunnel?
|
| Usually GPS devices assume you just maintain speed, which for
| most tunnels works out.
| poisonoushydra wrote:
| This is just one more reason to use a secure operating system
| such as GrapheneOS which has implemented a sensors toggle for all
| apps:
|
| https://grapheneos.org/features
|
| "Sensors permission toggle: disallow access to all other sensors
| not covered by existing Android permissions (Camera, Microphone,
| Body Sensors, Activity Recognition) including an accelerometer,
| gyroscope, compass, barometer, thermometer and any other sensors
| present on a given device. To avoid breaking compatibility with
| Android apps, the added permission is enabled by default."
| afavour wrote:
| On the other hand, the nature of Apple's BDFL ownership means
| that they could very easily add a permission prompt in an iOS
| release, allowing them to default to disabled, then tell app
| developers to update their code or go to hell. They've done it
| before with other APIs.
|
| In fact they've already done this on the web: the DeviceMotion
| API is behind a permission prompt. I'm surprised the same isn't
| the case for apps.
| derekjdanserl wrote:
| If Apple did that, giant app developers would whine about it.
|
| Google was basically responsible for locking down the
| DeviceMotion API.
| e_proxus wrote:
| Giant app developers _do_ complain about it (see the ad
| tracking debacle). That hasn't stopped Apple in the past.
| afavour wrote:
| IIRC Apple locked down the Contacts API precisely because
| giant app developers were abusing it. And look at the
| recent ad tracking stuff that Facebook hates: I don't think
| Apple is all that afraid of angering developers, big or
| small.
| SubzeroCarnage wrote:
| My https://divestos.org offers per-app sensors permission
| toggle and a global sensors/camera/mic toggle to many more
| devices.
| felipesoc wrote:
| One thing I thought regarding the new iOS IDFA rules is that
| someone could fingerprint people by using accelerometer and touch
| gestures to create some sort of new IDFA shared across apps.
| _trampeltier wrote:
| Does a website also have access to the accelerometer data (via
| browser)?
| krausefx wrote:
| On iOS, it used to be the case (https://krausefx.com/blog/ios-
| privacy-whats-the-user-doing), however with iOS 13 (https://git
| hub.com/w3c/deviceorientation/issues/57#issuecomm...) this has
| been addressed.
| XCSme wrote:
| https://developer.mozilla.org/en-US/docs/Web/API/Acceleromet...
|
| https://developer.mozilla.org/en-US/docs/Web/API/Gyroscope
|
| To use this sensor, the user must grant permission to the
| 'gyroscope' device sensor through the Permissions API.
| jonplackett wrote:
| The flip side of this argument is that having to explicitly allow
| accelerometer use is a bit of a pain - especially on the web
| where it's quite nice to just be allowed to make your design
| react to device motion without having to ask.
|
| Maybe they could just reduce the sensitivity slightly to prevent
| things like speech recognition working (though I am skeptical of
| that working in the real world)
| aaaaaaaaaaab wrote:
| >it's quite nice to just be allowed to make your design react
| to device motion without having to ask
|
| IDGAF about your design. I want my privacy.
| jonplackett wrote:
| I think there are multitude more invasive ways to invade your
| privacy than allowing access to the accelerometer.
|
| I just think this so massively overblown - especially for a
| web page that has soooooo many other ways to track you.
| nemetroid wrote:
| > especially on the web where it's quite nice to just be
| allowed to make your design react to device motion without
| having to ask.
|
| What kinds of motions and reactions would that be, beyond
| rotations (which are a much higher-level API than raw
| accelerometer data)?
| jonplackett wrote:
| Not talking about raw data. Clearly that isn't needed for the
| web. But my point is that it got thrown out with the bath
| water.
| afavour wrote:
| The web has a DeviceMotion API that provides such higher
| level data:
|
| https://developer.mozilla.org/en-
| US/docs/Web/API/DeviceMotio...
|
| Originally it wasn't behind a permission prompt so you could
| do the little design flourishes the OP described. But now you
| have to request access. Orientation change events (i.e.
| portrait to landscape) remains accessible without
| permissions, though.
| nemetroid wrote:
| > the little design flourishes the OP described
|
| And what flourishes are those?
| afavour wrote:
| An example I've seen (I forget where but hey, it won't
| work now anyway) is to move some background elements to
| create a parallax effect, like iOS itself does:
|
| https://www.idownloadblog.com/2013/06/28/ios-7-parallax-
| effe...
|
| I'm not trying to make out that it's a crucial feature or
| anything but it's a useful case study in permission
| gating things: it's small enough that you'd never trigger
| a permission prompt to ask to do it, so you just don't
| instead, and lose a class of nice subtle design flourish.
| Pulcinella wrote:
| Just FYI for anyone wondering: I believe this parallax
| effect specifically uses the UIMotionEffect API. It's
| designed to be a simple and straightforward way to
| implement these kinds of effects without the developer
| having to worry about cleaning up the raw, noisey motion
| data.
|
| It has a few limitations/features. I don't think it
| necessarily always runs at the screen refresh rate. It
| will also "self level" after a while. So if the user
| rotates their device and this causes a UI effect, if they
| hold their phone still the effect will reset after a few
| seconds.
|
| https://developer.apple.com/documentation/uikit/uimotione
| ffe...
| acomjean wrote:
| Interesting.
|
| Apple seems to track the accelerometer data in the background.
| (Why health app can tell you about steps and stairs...)
|
| But beyond that data leakage is an interesting problem.
|
| 10 years ago I started working at a company that did home power
| monitoring. We used my bosses house to test. When he went on
| vacation you could clearly see it in the power use. The daily
| rhythms of a home (laundry on wed, out late on certain nights ),
| when they cooked. It all had become very apparent under the guise
| of just monitoring how much power you were using. We switched to
| selling to businesses shortly after which was much better. Though
| those that wanted to generate as much as they used and monitored
| it were interesting and provided good feedback on the product.
|
| Our Big Boss's said his wife got a little aggravated with him,
| when he noted she had come in early (you can keep your toys just
| don't talk to me about it), and he noted his house cleaners
| operated by turning on all the lights in his house, and turning
| them off only when finished cleaning a room...
|
| Its a weird world, and the data you put out there might say more
| than you think.
| DeRock wrote:
| This type of stuff has come a long way, eg. see
| https://sense.com
|
| Its not just overall electricity use over time, but by doing
| high frequency spectral analysis, they can identify the type of
| load, eg. your washing machine is running, or your oven is on.
| acomjean wrote:
| That was just starting to happen when I left. We would just
| put a current transformer on the mains and each circuit and
| label it to try and glean details. It was a difficult
| install, and this new kind of install is way easier .. We
| wondered how well it could separate out the individual
| circuits.
| bentcorner wrote:
| For Android a fun toolkit to play with the accelerometer is
| phyphox:
| https://play.google.com/store/apps/details?id=de.rwth_aachen...
|
| My favorite trick is turning on the spectrum histogram history
| graph and placing the phone on a computer with a spinning HDD -
| you can trivially determine the RPM of the HDD from the spike in
| the graph just by eye.
| Aachen wrote:
| Huh, the spectrum goes to a few hundred hertz (edit: 250 to be
| precise, on Android 11, Samsung high end device (but second
| hand, the price new is ridiculous)). I have indeed measured a
| few 50 Hz movement before and was already surprised that worked
| properly, but the scale doesn't go to even one thousand. How do
| you read 5400/7200/... rpm? The magnetic spectrum is even
| worse, going until 50 Hz. Or are you talking about the audio
| spectrum? I wanna test it now but I don't have hard drives on
| hand anymore...
| bentcorner wrote:
| 7200 rpm is 120 hz and 5400 rpm is 90 hz. You should see
| spikes at these frequencies on the acceleration spectrum
| tool. The history view makes these spikes very apparent.
|
| I'm using a OnePlus 6t and mine goes to 200hz.
| vletal wrote:
| > Now, if this social app is reading accelerometer data on your
| phone as well as the passenger's phone, the app can easily figure
| out that both phones experience the same vibration pattern. ...
| Don't be surprised if you receive a recommendation from the app
| to add this passenger as a friend.
|
| Overall I find the article interesting but this quote is
| borderline tinfoily. Given the amount of noise in the
| accelerometer data and signal s much closer to the sensor than
| the bus itself - such as body movements, it would be hardly
| precise. Moreover the cost of doing all that research and
| computation as well as data transfer would hardly pay off.
| jrootabega wrote:
| It could easily be/have been a success story for contact
| tracing.
| ChicagoBoy11 wrote:
| except for, you know, the "we totally violated your privacy"
| part of it.
| jrootabega wrote:
| People would volunteer their data for it
| wongarsu wrote:
| If they volunteer, why not just use GPS, or Bluetooth
| LowEnergy? The accelerator seems to shine mostly as a
| convert vector.
| xattt wrote:
| Is the accelerometer sensitive enough to detect vibrations from
| sound and voices?
| TedDoesntTalk wrote:
| Yes - read the article
| api wrote:
| Sounds plausible to me. The question is whether anyone is
| really using this technique. Sounds like it would require
| nontrivial bandwidth and analysis.
| Nextgrid wrote:
| I recall that Snapchat explicitly mentioned accelerometer
| data in their privacy policy - why would you mention it
| unless you did or have plans to use accelerometer data in the
| future?
|
| I don't think it would require significant bandwidth; the
| data is just integers which can be collected, compressed and
| uploaded asynchronously (as part of another heavy upload such
| as someone sending a picture). The analysis part could be
| similar to how Shazam works, but that can be done on the
| server side so on-device performance isn't a concern.
| jcranberry wrote:
| A single simple would be three doubles and a timestamp (64
| bit int). Accelerometer max update rate is 100hz. So all
| possible samples each second would be 3200 bytes. So
| bandwidth doesn't appear to be a big issue.
| pantulis wrote:
| Which also means reduced battery.
| Nextgrid wrote:
| Most of the aforementioned apps already have autoplaying
| media and/or keep the camera running in the background
| (officially for quicker access to it when the user opens
| the camera view, as it normally takes a second or so to
| initialize it). Seems like collecting accelerometer data is
| a drop in the bucket in comparison.
| enriquto wrote:
| > The question is whether anyone is really using this
| technique.
|
| No. This is not _at all_ the question. A possible privacy
| breach is a serious issue, regardless of whether there is a
| working POC. If this data is somehow compromised, a stalker
| could get your identity just by following you a few minutes
| on the street.
| charcircuit wrote:
| a stalker wouldn't be able to accelerate the same as you
| shagie wrote:
| If they were on the same public transport vehicle, that
| would likely be a different situation.
| vletal wrote:
| Sure, but the article makes it seem that this is a thing
| done in a wild on a mass scale which is implausible.
| amelius wrote:
| The app could figure out who you are traveling with (two phones
| with roughly the same accelerometer data at the same time).
| themanmaran wrote:
| I think there would be far too much noise. The accelerometer
| data is going to be different based on a number of factors:
|
| Orientation? Is the phone in your hand? Your pocket? Your
| purse? Front seat / back seat?
|
| By way of comparison I worked on some automatic breaklights
| that trigger when an accelerometer detects you slowing down
| (bikes, skateboards, scooters). It turned out to be way more
| complicated that we expected. Hitting potholes, naturally
| slowing when you go uphill, taking a turn.
| Nextgrid wrote:
| I think the key is that the data would be in sync. You
| don't particularly have to care what the vibration is or
| which direction, the important bit is that these patterns
| line up with similar patterns collected from the other
| phone.
| genewitch wrote:
| I've mentioned this before, but the Bosch 9-DOF sensors are
| accurate and have enough fidelity to track me walking
| through my house while sitting in the back room on a desk.
| That's the accelerometer. The gyros can detect music
| playing at the opposite end of the house assuming the
| speakers are big enough - phone playing YouTube, no, but
| sound bar, yes.
|
| Make no mistake that MEMs sensors are really very good.
|
| I was trying to wire something together to track what
| vehicles were travelling down my forest road and left the
| room with the data streaming, and came back to be
| impressed.
| V99 wrote:
| It's an accelerometer and gyroscope. The acceleration
| is/can be reported relative to gravity, which always points
| down.
| robotresearcher wrote:
| You can't tell what component is due to gravity and what
| is not, without other information.
|
| This is the equivalence principle of general relativity,
| no less.
| [deleted]
| coldcode wrote:
| Also remember that apps do not run continuously in background,
| which would make the data only useful if the user was actively
| running your app.
|
| I don't believe the data is precise enough to do much that
| could be nefarious.
|
| Also trying to matching two phones (without location info) that
| have the same highly imprecise vibration is not worth the
| effort on the server side.
| pupdogg wrote:
| Just an FYI, Apple does give its developer the ability to
| have the app wake up from background on-demand or at
| scheduled intervals to perform specific tasks. This is
| something that can be done as long as the phone is ON and
| connected to the public gateway either via cell towers or
| WiFi.
|
| An example would be the Facebook app icon with notification
| count or the Mail app with unread emails count. This counter
| is updated based on background processing of Fb or email
| notifications.
| brundolf wrote:
| I don't know exactly how it works, but I know notifications
| are their own separate concept that gets handled by the
| system and doesn't require the app to be running arbitrary
| code in the background
|
| There is also the "allow background activity" permission
| though, which I'm not sure the bounds of, but you can
| disable it
| sroussey wrote:
| Notifications and background activities are orthogonal for
| the use case you mentioned.
|
| Background activity on iOS is severely restricted and
| mostly relegated to finishing a long or regular upload or
| download.
|
| Unless you are a phone communication app -- and a reason
| why you may see voice added to apps.
| emilfihlman wrote:
| I find it pretty funny, since to me that seems completely
| normal and easy and wouldn't even require much from an
| algorithm to implement.
| Nextgrid wrote:
| Vehicle-induced vibrations would result as significant
| (overpowering any noise) peaks on one or more accelerometer
| axis, and their timestamp (relative to other peaks) will
| precisely align with peaks on any other device on that vehicle.
|
| As a layman I think you can just sum all axis for each person,
| overlay the resulting track with everyone else's and try to
| find a position where enough peaks correlate (constrained
| within a 5 minute timeframe from the on-device timestamp to
| account for clock drift while limiting the search space) and
| that should work well enough.
|
| I'm sure the sociopaths working for Facebook will have a
| smarter way of doing this that's even more accurate.
| EarthLaunch wrote:
| The timing. Just look at two phones that are vibrating for
| the exact same length of time; they are in the same vehicle.
| [deleted]
| silon42 wrote:
| You can do obvious things, like detect when the user put down
| the device after the ad stats playing.
| vletal wrote:
| How does it relate to the paragraph about pinpointing precise
| location which the original comment refers to?
| runjake wrote:
| Get a story, such as "Facebook using Core Motion APIs to uniquely
| identify users!" to go viral, and Apple will patch it real quick.
|
| In fact, Facebook may actually be doing this now, after the
| recent actions taken to nerf advertisers (yay).
| davbryn1 wrote:
| Well, Facebook do use accelerometer for 360 panorama view. Could
| be as simple and they initialise coroMotion when the app becomes
| active in order to have their render react without a new
| initialisation each time?
| durnygbur wrote:
| Default permission for all apps to use accelerometer, recognizing
| sounds from the accelerometer? This would explain the situation
| when I talk about something nearby my iphone and then relevant
| ads appear in the internet browser on the device, or within local
| network.
| matheusmoreira wrote:
| > I talk about something nerby my iphone and then relevant ads
| appear in the internet browser on the device
|
| How do I stop this?
| matthewmacleod wrote:
| You can't stop it, because it isn't happening to begin with.
| yosito wrote:
| The microphone also explains this. I keep a tight reign on
| which permissions I give apps. I rarely get accurately targeted
| ads. Last week I suddenly noticed that the ads I was seeing on
| Facebook were matching the conversations I'd had that day. I
| immediately knew an app had been eavesdropping on me. Turns out
| I had given Instagram microphone and camera permission "while
| the app is in use" earlier in the day to try out an Instagram
| feature I was curious about, and forgot to turn it off. Even
| though I wasn't using the camera or mic intentionally,
| Instagram was still spying on me. This really should be illegal
| behavior by apps.
| ryantgtg wrote:
| How long does the app stay in use? I have insta installed
| (for a business that I'm slacking on) and I open it about
| once a month for roughly 1 minute. Maybe I should just
| uninstall and reinstall it each time I need to use it.
| charcircuit wrote:
| It was probably a coincidence or the targeted ad simply was
| accurate.
| huntertwo wrote:
| Tangentially related:
|
| It's wild what new data can be used for fingerprinting. [1]
| describes using magnetic signals to fingerprint a device. [2]
| describes identifying inputted text from CPU interrupt data.
|
| I wouldn't be surprised if health data can also be used to
| fingerprint users, even across devices. I wonder what lower level
| runtime information (e.g. CPU interrupt data) is available to
| apps.
|
| [1] https://dl.acm.org/doi/abs/10.1145/3319535.3339810 [2]
| https://www.repository.cam.ac.uk/handle/1810/254306
| zupreme wrote:
| So...nobody wants automatic portrait/landscape rotation anymore?
| neoberg wrote:
| You don't need precise sensor data to achieve this. Afaik IOS
| notifies the app when the orientation changes.
| hbn wrote:
| Every app isn't re-implementing auto-rotate by reading gyro,
| the OS handles that
| paxys wrote:
| The most blatant (mis)use of this was Uber using vibration data
| to figure out which drivers were getting notifications from the
| Lyft app while they had Uber running.
| 43920 wrote:
| Source?
| waylandsmithers wrote:
| This would support the theory that Facebook can listen to you and
| serve ads on things you talk about even if you haven't given it
| microphone access right? I'd assume they have enough data to be
| able to translate vibration patterns into language.
| nemacol wrote:
| Reminds me a bit of these stories 10 years ago.
|
| https://www.wired.com/2011/10/iphone-keylogger-spying/
|
| "The accelerometers in many smartphones could be used to decipher
| what you type into your PC keyboard. "
| kypro wrote:
| I wonder if there is a market for a smart phone with a hardware
| disconnect switch for all of its sensors? Mic, accelerometers,
| camera, ambient light, etc?
|
| I'd love to be able to flick a switch and just disable
| everything. I'm paranoid about my devices listening to me without
| my permission. The only issue is that for such a feature to be
| useful it probably couldn't disconnect everything, wifi and
| mobile data would probably need to remain software switches for
| example.
| fsflover wrote:
| > I wonder if there is a market for a smart phone with a
| hardware disconnect switch for all of its sensors? Mic,
| accelerometers, camera, ambient light, etc?
|
| https://puri.sm/products/librem-5
|
| https://puri.sm/posts/lockdown-mode-on-the-librem-5-beyond-h...
| makeitagoood wrote:
| Librem 5 is basically a scam at this point, many people who
| ordered it 4 years ago still haven't received it. It barely
| qualifies as a "mobile phone" with how bad it's battery life
| and efficiency is. Plus it's 1200$. Hard Pass.
| fsflover wrote:
| Did you hear about the supply chain problem, which even
| Apple suffers from?
| sva_ wrote:
| The Pinephone also has hardware switches:
|
| https://wiki.pine64.org/wiki/File:Pinephone_backside.png
|
| Wish the hardware was better.
| matheusmoreira wrote:
| > Wish the hardware was better.
|
| Same here, the hardware is really underwhelming.
| weberer wrote:
| >Wish the hardware was better
|
| Well I have good news for you
|
| https://www.pine64.org/2021/10/15/october-update-
| introducing...
| sva_ wrote:
| Well that's great news!
|
| Sadly, the camera is still a potato, relatively speaking,
| compared to ie Pixel 6 Pro or S21 Ultra.
|
| And the camera is pretty much the main criteria of
| choosing a phone for me, because I like the outdoors a
| lot, and I take many photos (and I can't get myself to
| carry around a 'real' camera - or getting into that whole
| topic.)
| rjsw wrote:
| The switches don't disable the accelerometer and
| magnetometer.
| fsflover wrote:
| But Pinephone's switches are not easily accessible: You
| can't switch your microphone on while receiving a call
| (unlike on Librem 5). Also, no lockdown mode for sensors.
| swiley wrote:
| IMO: the software on the PinePhone is _significantly_
| more trustworthy than most devices (as long as you 're
| not careless or install non-free apps.) The switches are
| there more for the sake of completeness but I would just
| as soon trust muting the microphone in pavucontrol.
| fsflover wrote:
| It depends on your threat model.
| megous wrote:
| You can't really trust HW switches either. Someone who
| has physical control over the phone for a while can
| easily short the switch so that it's basically on all the
| time no matter the position. (they can do it at the same
| time they'll be installing the SW backdoor)
|
| ;)
| skinkestek wrote:
| It might be meant as a joke but I am so tired of every
| comment that seems to imply that trying to do anything is
| pointless:
|
| Yes, a significantly advanced adversary can always get
| your communications if they want, but every time someone
| does choose the more secure option it raises the bar for
| them.
| megous wrote:
| What's the point of security measures if you just dismiss
| their weak points?
|
| "FBI is comming for me, but I have my HDD encrypted..."
| Well, how well did HDD encryption serve that guy who the
| FBI just pulled the turned on/unlocked notebook from
| before he noticed what's going on and was able to react?
| He might just as well not bothered, when he knew "FBI" is
| in his threat model, and didn't account for this obvious
| attack in any real way.
| skinkestek wrote:
| It is about the tone of the message.
|
| If you had instead written something along the lines of
| "for those who have mighty adversaries and who actually
| need this for their own security, one should be aware
| that things like hardware switches only go so far" and
| then an explanation.
|
| Instead you wrote it in a way that I and probably a lot
| of others took to mean: even hardware switches doesn't
| matter.
| fsflover wrote:
| > Someone who has physical control over the phone for a
| while
|
| So you shouldn't give your phone to anyone you do not
| trust?
|
| (Also, AFAIK, you can simply reinstall all software
| yourself.)
| megous wrote:
| If using trusted software is enough, then HW switches are
| pointless anyway.
| fsflover wrote:
| Nothing is "enough". It's defense in depth.
| viccuad wrote:
| someone should just 3d print a back case for the
| pinephone that exposes them. Or better, instruct on how
| to cut the current case, and 3d print a lever system that
| matches the hole, for easily action on the switches from
| outside.
| fsflover wrote:
| > someone should just 3d print a back case for the
| pinephone that exposes them.
|
| I have a Pinephone. Those switches are _very_ tiny and
| probably not designed for everyday switching, even if you
| connect them to larger ones.
| kypro wrote:
| Thanks for the link. This looked too good to be true until I
| clicked the order now button... $1,199...
|
| I normally go for budget smart phones in the range of $100 -
| $200. I'd pay more for something with decent build quality
| and a privacy focus, but $1,199 is a little pricey for me.
| DeathArrow wrote:
| Look for Pinephone. It has about as powerful hardware wise
| as Purism (4x Cortex A53 cores for both) but is $150.
|
| https://pine64.com/product/pinephone-beta-edition-linux-
| smar...
| fsflover wrote:
| > It has about as powerful hardware wise as Purism
|
| It really isn't:
|
| _The i.MX 8M Quad is better than the Allwinner A64: 30%
| faster CPU clock speed, 140% faster RAM standard, 140% 21
| better OpenGL performance, USB 3.0 and support for higher
| resolution cameras._
|
| https://forums.puri.sm/t/comparing-specs-of-upcoming-
| linux-p...
| floatboth wrote:
| Both are about as bad. No matter how high you clock it
| and how good your RAM is, a Cortex-A53 is still an A53.
| fsflover wrote:
| It depends on what you are going to do with it. Librem 5
| smoothly runs 60 fps full HD videos and plays 3D games.
| makeitagoood wrote:
| Even if it was 300$ it would still be a terrible phone.
| It's extremely inefficient and battery life is hilariously
| bad, the device itself is advertised as an extremely secure
| device but it is actually not secure at all, you can't even
| easily update the modem firmware. The company itself has a
| history of lying and their CEO is a habitual liar. The
| PinePhone, while not secure either, provides basically the
| exact same thing at a fraction of the cost (150$) and
| slightly weaker specs. Pine64 is now making a PinePhone Pro
| which is significantly faster than the Librem 5 at a
| fraction of the cost so why even bother with Purism at all?
| fsflover wrote:
| > It's extremely inefficient and battery life is
| hilariously bad
|
| This is false: The phone has no suspend mode yet, and its
| battery life is 10+ hours. After it's implemented, it
| will be on pair with an Android:
| https://source.puri.sm/Librem5/community-
| wiki/-/wikis/Freque....
|
| > you can't even easily update the modem firmware
|
| This is also false: You can upgrade the firmware.
| https://source.puri.sm/Librem5/community-
| wiki/-/wikis/Freque...
|
| > The PinePhone, while not secure either, provides
| basically the exact same thing at a fraction of the cost
|
| This is not the exact thing at all. Apart from huge
| differences in the performance [0], Pine64 does not
| develop any software and most Pinephone users are using
| Phosh developed by Purism. Linux phones can't be
| sustainable without professional developers, just with
| volunteers.
|
| Also, both phones are more secure than Android, depending
| on what you understand by "security":
| https://source.puri.sm/Librem5/community-
| wiki/-/wikis/Freque...
|
| [0] https://source.puri.sm/Librem5/community-
| wiki/-/wikis/Freque...
| mindslight wrote:
| > _I 'm paranoid about my devices listening to me without my
| permission_
|
| "Your devices" aren't listening to you. What is listening to
| you is hostile third party software that you've been goaded
| into running on your devices (whether by javascript, apps,
| chipset, or as part of the OS), that has been insufficiently
| sandboxed. Hardware switches are just mitigations for an
| insecure OS that violates its fiduciary duty to the user, and a
| less good solution than having those capabilities built right
| into the OS. If sensor switches became popular, then hostile
| apps could just refuse to work when those sensors were off -
| just as hostile apps will refuse to work if you do not grant
| them requested permissions. Whereas a real user-representing OS
| would allow one to designate that an app should receive
| synthetic data for any sensor - eg set a fixed "GPS location"
| and then add some plausible sounding noise so that an app
| couldn't tell it apart from a stationary phone.
|
| But what is really needed for sustainable user privacy is user-
| representing software that talks to adversarial counterparties
| solely through well-defined protocols. This isn't necessarily
| workable for new innovations, but for all well established
| technologies (messaging, pictures, video chat, social
| networking, message boards, etc) there should be Free clients
| that interoperate with the proprietary systems. Much has been
| said about "breaking up" Big Tech to constrain their power, but
| mandating such interoperability would be a much better approach
| to antitrust.
| dotancohen wrote:
| A guy that I studied with had his company bought by a tech giant.
| Not FAANG, but a big company that you've heard of.
|
| Their product - in production - was to map establishments such as
| stores and provide data about what the clients were looking at.
| Did you walk past the mens' shirts and turn your body? Noted. Did
| you stop at the condoms? Noted. This was all done with the
| accelerometer, if the user had a "compatible app" installed. A
| lot of apps carried their technology from what I understand.
|
| I actually thought that this was a well-known use of our devices'
| accelerometer until I read the responses in this thread.
| charcircuit wrote:
| accelerometers drift WAY too much for that to work
|
| maybe it worked in tandem with reading the strength of wifi
| access points or tried to use GPS (this might not work well
| indoors)
| relaxing wrote:
| You're right, you probably know more about it than the
| academic who founded a company on their research on the
| subject.
| [deleted]
| dotancohen wrote:
| I don't know the whole tech stack, I only got this much
| information after surreptitiously bumping into him one day.
| They had a few dozen devs and years invested in the company -
| and this was in 2017 or 2018. I'm sure that there were other
| technologies involved, in fact I do think that both GPS and
| some in-store box which was already used to record passing
| IMEIs were involved.
| lotsofpulp wrote:
| >I only got this much information after surreptitiously
| bumping into him one day.
|
| I am confused how "surreptitiously" could be used in this
| context. Were you spying on him?
| psyc wrote:
| I'm guessing _serendipitously_.
| dotancohen wrote:
| I was not planning on meeting him - but we sat next to
| each other on the train. The previous time that I had
| seen him was a decade prior when he bought my modified
| N-Gage.
| lotsofpulp wrote:
| Ah, then as psyc wrote, serendipitously would be the
| word.
| sroussey wrote:
| Combine with Wi-Fi or Bluetooth beacons. But really, I can
| only see this working on android unless the app is on screen.
| tombert wrote:
| Actually a pretty good idea for a business if I'm being honest.
| Like, it's horrifying, I don't like that this is a thing, but
| it's fairly valuable data for a business.
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