[HN Gopher] WiFi can read through walls
___________________________________________________________________
WiFi can read through walls
Author : geox
Score : 143 points
Date : 2023-09-11 16:45 UTC (5 hours ago)
(HTM) web link (news.ucsb.edu)
(TXT) w3m dump (news.ucsb.edu)
| Animats wrote:
| Outline detection of metal objects at distance should be good for
| remote gun detection.
| blobbers wrote:
| Stupid question as someone who worked on wifi for many many
| years: What is the point of this? How is this remotely useful?
| There are tons of better technologies to use?
|
| Let me guess, this thing puts the wifi into some constant
| transmit mode and measures loss rates as it passes through
| objects, and scans in some pattern, measuring loss rates at the
| other side.
|
| Is this just packet based radar? Is this a cute way of saying
| "using the 5GHz band to scan through walls when you have a
| receiver on the other side of your object"?
|
| Here's the thing: different materials absorb / reflect radio
| waves with different characteristics. You could just as easily
| make these letters out of a completely different material that
| doesn't remotely resemble a letter and it could look exactly like
| a letter.
|
| How is this useful? And why is wifi the medium to do it. You
| can't just do this with a regular old driver. Your normal driver
| will be selecting antennas, adjusting rates for loss rates. This
| is clearly a dedicated radio with some open source driver that
| they've hacked to do this.
|
| Ugh. This just seems like a dumb waste of time. This isn't even a
| passive radar, as it requires there to be a receiver on the other
| side. There is no bouncing back of signals.
|
| "It does not require any prior RF data for training a machine
| learning system for RF sensing." Yes, but it does require very
| specific material characteristics that it is trying to detect at
| fixed distances. Namely edge keller cones on specific materials,
| and hoping that other materials don't replicate similar patterns.
| kenhwang wrote:
| Oh, hey, I knew someone who helped with research on this while
| I was at UCSB over a decade ago.
|
| From the way they described the goals of their research, it
| wasn't so much using WiFi as radar with specially flashed
| router drivers doing emitting and receiving, that's just a
| research convenience.
|
| The whole point is to passively detect objects using already
| existing WiFi signals. It's easy enough to figure out where the
| router is, and if the router is regularly noisy enough, the
| idea is they would have enough data to work with.
|
| The research results from a decade ago was able to pinpoint and
| uniquely identify humans and weapons. Not hard to guess how
| that could be useful to the DoD.
| sgirard wrote:
| I would love to be able to image elements _inside_ a wall
| cavity: studs, pipes, ductwork, electrical lines. I don 't know
| if it's possible with this technique, but maybe someday these
| ideas will lead to something like an x-ray for building
| structures.
| kenhwang wrote:
| You're describing a modern off the shelf studfinder. Those
| already use magnets, radar, and ultrasound to detect studs,
| pipes, and wires.
| gweinberg wrote:
| I've got a stud detector and it works like crap. But it's
| pretty old, maybe new ones are better.
| jdjdjdjdjduuuu wrote:
| Hack your internet and see everything in your house could be
| one use?
| andrewtesting44 wrote:
| Just to clarify, the receivers are on the same side as the
| transmitters
| KeplerBoy wrote:
| We call this a monostatic radar.
| [deleted]
| Fabricio20 wrote:
| One use that personally springs to mind, is if this technology
| is developed enough, SWAT/Rescue teams could use this to find
| where people are inside buildings. No need for letter-reading
| precision, just good enough to be easily deployable on-site and
| work well enough to find where people/bodies (big masses of
| water?) roughly are.
| stagger87 wrote:
| Yes, essentially radar. Wifi is the medium because you already
| have a router in your home.
|
| This sort of capability is being introduced into the newest
| WLAN standards and is being promoted as the next step towards
| smart homes and devices. The idea being that a standard router
| can be used to detect human presence, and therefore do things
| like turn on/off lights, HVAC, etc. This might make even more
| sense in the commercial space.
|
| This would be as far as I'm aware the first attempt at doing
| something like this without additional hardware (mounted
| sensors). It should in theory lower the barrier to entry even
| further.
|
| There are higher frequency variations of this that could in
| theory do things like detect breathing. Some people are talking
| about it being like the new lifeline button or baby monitor.
|
| How well it's implemented will ultimately determine it's
| usefulness IMO.
| madars wrote:
| Very impressive! Famous previous work captured moving objects and
| did gesture recognition through the walls
| https://people.csail.mit.edu/fadel/wivi/project.html but this new
| research can capture still objects.
|
| UCSB paper:
| https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=101...
| ("Analysis of Keller Cones for RF Imaging")
| throw0101c wrote:
| This is not (completely) new. 2019 paper entitled "Passive Radar
| based on 802.11ac Signals for Indoor Object Detection":
|
| * https://ieeexplore.ieee.org/document/8904842
|
| There is an IEEE Working Group to create an extension for 'active
| radar':
|
| > _IEEE 802.11bf will enable stations to inform other stations of
| their WLAN sensing capabilities and request and set up
| transmissions that allow for WLAN sensing measurements to be
| performed, among other features. WLAN sensing makes use of
| received WLAN signals to detect features of an intended target in
| a given environment. The technology can measure range, velocity,
| and angular information; detect motion, presence, or proximity;
| detect objects, people, and animals; and be used in rooms,
| houses, cars, and enterprise environments. The targeted frequency
| bands are between 1 GHz and 7.125 GHz (MAC /PHY service
| interface) and above 45 GHz (MAC/PHY)._
|
| * https://standards.ieee.org/beyond-standards/ieee-802-11bf-ai...
|
| Presentation on the extension and Wi-Fi sensing:
|
| * https://www.youtube.com/watch?v=I3GmgO9biH87&t=5m10s
| pmontra wrote:
| This is from 2013 https://dspace.mit.edu/handle/1721.1/82183
| erikerikson wrote:
| Yes, I have met technologists who claimed to be working on the
| tracking of people in their homes using Wi-Fi. There are great
| uses such as elder health monitoring (i.e. not fallen and can't
| get up) but others too...
| godelski wrote:
| I remember seeing some presentations about WiFi gait
| recognition too. Quick google turned up this __2016__ paper
|
| https://dl.acm.org/doi/10.1145/2971648.2971670
| andrewtesting44 wrote:
| It is novel in terms of using physically accurate models such
| as edge diffraction to localize edges instead of the object as
| a whole. Most narrowband radar based imaging approaches
| consider extended objects as a collection of omnidirectional
| point scatterers, which may not be the most optimal
| representation....
| DrThunder wrote:
| This isn't really that different from sonar is it?
| pcthrowaway wrote:
| 'read' is misleading. It's determining what letters are
| represented by 3-dimensional letters.
|
| It _can 't_ read 2-dimensional print on paper. Now _that_ would
| be a massive (and terrifying) accomplishment
| solardev wrote:
| Man, I'd settle for wifi that just lets me internet through walls
| reliably.
| stronglikedan wrote:
| My simple 5yo, non-wifi6 router gets me a reliable signal
| through at least two walls, so I would imagine any somewhat
| modern router would meet your requirements.
| solardev wrote:
| In all seriousness, it depends on your frequency used,
| building materials, national limits on WiFi output power
| (which some routers/firmwares respect more than others), etc.
|
| 5 GHz in particular has trouble passing through concrete and
| metal. If you have a small wood house or apartment it often
| isn't an issue, but if your office has a lot of concrete and
| steel, etc. it could be problematic. Those enterprise mesh
| networks exist for a reason :)
|
| https://blog.ibwave.com/a-closer-look-at-attenuation-
| across-...
|
| https://help.keenetic.com/hc/en-us/articles/213968869-Wi-
| Fi-...
| doubled112 wrote:
| The metal mesh in some plaster walls seemed to cause a lot
| more signal drop than I expected in one place I lived.
|
| 5GHz was basically a no go. It wasn't a huge loss since few
| devices were running it back then.
| NoZebra120vClip wrote:
| When I was in high school, my parents hired some
| contractors to put an addition on the family home and do
| some improvements in most of the rooms.
|
| So the most arduous part of the whole job appeared to be
| the demolition to start with. They started pounding into
| the thick plaster walls, and revealed a thick mesh of
| solid steel reinforcement. Of course, that took ages to
| take out, wherever they had to deal with such a wall.
|
| And you know what? I was absolutely appalled by the
| chintzy material that went in to replace it. They just
| brought this drywall, you know, and I got to touch it and
| examine it, and I couldn't believe how flimsy it was,
| when compared to the reinforced plaster they'd just taken
| out. I mean, like, there were cost and time
| considerations, but it seemed like a travesty to me. Like
| we were sacrificing half of our solid, valuable home for
| a mere facsimile in the other parts.
|
| Today, the WiFi is fairly bad. My dad only has the one
| router in a distant corner of the den. I don't know how
| reception is directly upstairs, where his bedroom is, but
| the downstairs bedroom can barely keep a signal going at
| the best of times.
|
| That home renovation was happening around 1988, so
| possibly too early to really think of putting Ethernet in
| every room, but my dad would've been the dad to do it.
| throw0101c wrote:
| > _They just brought this drywall, you know, and I got to
| touch it and examine it, and I couldn 't believe how
| flimsy it was, when compared to the reinforced plaster
| they'd just taken out._
|
| Exactly what are you getting by having the 'less flimsy'
| plaster and what are you losing with the 'flimsy'
| drywall? (I ask this as someone with three uncles that
| work in construction/renos.)
| kenhwang wrote:
| The biggest benefit I've noticed with plaster walls is
| the soundproofing. There's more layers of much denser
| material.
|
| My walls are 1 inch of plaster with metal lath (vs the
| typical 1/2 thickness for drywall), on top of traditional
| wood slat lath, then insulation and studs. Typically if
| you have construction old enough for lath and plaster
| walls, they might also have independent studs per side,
| further isolating sound transfer.
| vel0city wrote:
| Sure, the drywall is flimsier than the plaster walls you
| had before but they are _way_ easier to work with, make
| modifications to, and repair. And for normal usage, they
| 're plenty reliable. The walls themselves shouldn't be a
| part of what makes the house "solid", that's the job of
| the framing _behind_ the plaster or drywall.
| samus wrote:
| > The walls themselves shouldn't be a part of what makes
| the house "solid", that's the job of the framing behind
| the plaster or drywall.
|
| It's actually a fairly recent trend to not build load-
| bearing walls anymore and instead really on a skeleton.
| Walks can very well be constructed to be load-bearing.
| But, as you indicate, the resulting building would be
| more difficult to modify.
| kenhwang wrote:
| My very modern many antenna WiFi6 router has a very hard time
| going through even one wall. Turns out metal lath and plaster
| walls do a very good job of blocking radio signals.
| whiddershins wrote:
| wooden lath and plaster the same. I assume it is the
| plaster, not the lath.
| brian-armstrong wrote:
| You ever finish working on something and then think to yourself,
| "damn, I just created something incredibly evil"?
| thomastjeffery wrote:
| How many steps removed is a bad actor from making it
| themselves?
|
| Usually, we can't rely on things simply not being invented, so
| we do the next best thing: invent it, and use the invented
| thing to learn how to manage the risk that thing introduced.
| flangola7 wrote:
| That's not secund best. You can not invent it in the first
| place too. We have intentionally throttled recombinant DNA
| research for decades.
| COGlory wrote:
| What recombinant DNA research do you believe is not being
| done?
| judge2020 wrote:
| 3-letter agencies have reportedly been using RF for similar
| purposes for almost a decade
| https://www.usatoday.com/story/news/2015/01/19/police-
| radar-....
| brian-armstrong wrote:
| So we agree it is evil then
| zaat wrote:
| I was working on a IT consolidation project in a remote country
| branch, replacing the old systems with those of the global IT
| infrastructure and a new local server managed by the global IT
| team. When I finished my work I was standing in the small
| servers room with the local IT admin, he said something that
| disclosed he felt there was nothing important for him to do
| anymore. The move was the right path for the business. I felt
| terrible.
| user_7832 wrote:
| Ethics really should be mandatory for anybody making/designing
| anything. Some unis do fortunately have mandatory ethics
| courses depending on your programme.
| dogman144 wrote:
| Already exists in prod. At a meetup several years ago, it was
| demonstrated that you could track a person's location in an
| adjacent room by triangulating Wi-Fi interference.
|
| I'm not into RF so this is a bit imprecise, but it took like a
| RPi with GNU radio, a second router, and some code to diff the
| signals into a location.
|
| The demos were compelling, you could see a heatmap of a user
| waving and so on. This is a product already sold.
| zerd wrote:
| The page, paper and video say that as well. The difference here
| is that this is tracing still objects.
| tomxor wrote:
| Somewhere.. Someone.. Who wrote down their wifi password, on
| their fridge, with giant 3d magnetic letters, is shitting
| themselves right now./jk
|
| Interesting paper though, I wonder what non-infosec applications
| it might have.
| ambrose2 wrote:
| What about a QR code that guests can scan to log into your WiFi
| without typing an explicit password.
| ericbarrett wrote:
| Unless I'm misunderstanding you, this already exists:
| https://qifi.org/
|
| Format is described on the page if you want to do it
| manually.
|
| Of course the plaintext password is still encoded in the QR
| code data, so it's not very secure, but great for home
| guests.
| netrus wrote:
| On my Android Samsung Galaxy, when I want to know the
| password of a saved Wifi, I generate a share-QR, screenshot
| it, and have a QR scanner scan the picture to extract the
| password. It drives me nuts, the password is clearly not
| secure/protected, still the UI will only give me the QR
| code, not the plaintext. PLEASE tell me I am just too
| stupid to find the right menue!
| rkwasny wrote:
| What did they use as a receiver? how RX Grid was build?
| rkwasny wrote:
| Details are here:
| https://web.ece.ucsb.edu/~ymostofi/WiFiReadingThroughWall
| mattw2121 wrote:
| Hopefully we aren't documenting company/government secrets with
| letter blocks that you purchase at Hobby Lobby.
| kristopolous wrote:
| "oh look there's the FBI guys again. Go get the giant foam
| typewriter letters from the back room. "
| dylan604 wrote:
| at least they a decent enough to drive around with SSID
| labeled "FBI Surveillance Van", so you just need to have an
| RPi scanning available SSIDs, and enable the SCIF-activate
| button when the van approaches
| woodrowbarlow wrote:
| PSA: Nokia is out there pitching a vision for what 6G mobile
| networks will look like, and they're pitching this as a _feature_
| of the media.
|
| Nakia wants 6G devices to act as 3D imaging clients, and for
| network operators to have access to a realtime, 3-dimensional
| visualization that can see right through walls.
|
| this was literally used as a plot point in one of the batman
| movies a decade ago to highlight how dangerously invasive tech
| can be.
|
| https://www.nokia.com/about-us/newsroom/articles/nokias-visi...
|
| https://www.bell-labs.com/institute/blog/building-network-si...
|
| > A very exciting innovation that 6G will bring to the table
| would be its ability to sense the environment. The ubiquitous
| network becomes a source of situational awareness, collating
| signals that are bouncing off objects and determining type and
| shape, relative location, velocity and perhaps even material
| properties. With adequate 6G solutions for privacy and trust,
| such a mode of sensing can help create a "mirror" or digital twin
| of the physical world in combination with other sensing
| modalities.
| Spivak wrote:
| Well, because it is a feature. It's really cool and I already
| have ideas for projects I want to do with it. An
| omnidirectional way to map an entire space that doesn't have
| the limitations of or require cameras is incredible. And one
| that I can potentially use to map myself as I walk around. It's
| basically the end game of motion controls.
|
| The popularity will explode the moment someone makes a
| commercial where someone is cooking with something messy and
| using their phone without ever touching it.
|
| It's the people who make or break it. "This technology is too
| dangerous and must be destroyed, but hold on I need to use it
| first because it's really useful" doesn't feel like the
| strongest condemnation.
| YakBizzarro wrote:
| The only result will be that the router of my neighbor,
| provided by his ISP, will happily reports the inside of my
| apartment. Sorry, I can be excited for a radar-based
| controller for a console, but as part of wifi, I can't really
| find any legit use
| Spivak wrote:
| I, maybe naively, assumed this capability will also comes
| to handhelds but yeah if it's only for stationary APs then
| it's kinda lame.
| solardev wrote:
| Beamforming around moving (or even static) obstacles?
| Integrated motion sensing with fewer false positives for
| smart bulbs, doorbells, whatever? Or more realistically,
| your TV can make sure you don't skip the commercials. I
| probably wouldn't use that stuff myself either, but it's
| interesting to think about.
|
| Why would I care that my neighbor knows we're home and
| moving around? If they really wanna creep on us, they can
| already use IR cameras or audio amplification or laser mics
| or whatever.
| rfrec0n wrote:
| Walls of homes are usually insulated enough to make an IR
| camera useless unless it's inside the home. It would be
| good for identifying cracks that heat can seap through
| though. Surveillance by laser microphones can easily be
| mitigated by curtains or blinds. Both of those also
| require the person spying to intentionally use them to
| spy. There is no legal commercial device that could
| prevent your neighbor's Xfinity Hotspot from selling what
| you do in your own home to Facebook/Google to use to
| target you with ads.
| OkayPhysicist wrote:
| It would come off as a bit paranoid, but chicken wire
| would block wifi signals.
| buran77 wrote:
| > If they really wanna creep on us, they can already use
| IR cameras or audio amplification or laser mics or
| whatever.
|
| There's always a more sophisticated way to do something
| bad. Why would that be a good reason to lower the bar for
| doing it?
| wahnfrieden wrote:
| US govt and military give a lot of money to Nokia
| Scanner771 wrote:
| Nokia has NSA rooms in their R&D offices. It's creepy.
| 37469920away wrote:
| What's even creepier is that parent company also owns
| Github.
| trilbyglens wrote:
| Cool another way to strip away peoples privacy.
| nighthawk454 wrote:
| Related:
|
| 2013 - gesture recognition from Wi-Fi
| https://wisee.cs.washington.edu/
|
| 2013 - see through walls with Wi-Fi
| https://people.csail.mit.edu/fadel/papers/wivi-paper.pdf
|
| 2023 - dense pose estimation from Wi-Fi
| https://arxiv.org/abs/2301.00250
| r00fus wrote:
| Impressive. Now how do we defend against malicious use of this
| POC?
| aarong11 wrote:
| Leave the microwave running
| RajT88 wrote:
| Build a detector which can differentiate from normal traffic
| and a "scan" like this.
|
| Wire up an RPI to a motor which reorients a 2.4ghz parabolic
| dish, first discovering the direction and elevation which
| best picks up the signal from the "scanner". Then, engage the
| old microwave emitter you've hooked up to the dish.
|
| You will like as not fry their equipment. Bonus: the attacker
| may never have children.
| samus wrote:
| That's the best part of it: the technique seems to be
| passive.
| ranting-moth wrote:
| Wouldn't you need two microwaves for each axis (XYZ), facing
| opposite direction? So six microwaves in each room. You have
| to remove the door switch because you need to leave them
| running 24/7.
| dylan604 wrote:
| let's not be silly. just put it in the attic so each room
| is covered centrally. you may need a higher wattage
| microwave though.
| ranting-moth wrote:
| Mine is around 800w. Would a single 1600w be as good in
| the attic centre as two 800w evenly spaced?
| swader999 wrote:
| This is what I use: YShield RF Shielding Paint - 5L Bin - HSF54
| - Blocks Wifi, Smart Meters, Cell Phones, Etc.
| https://a.co/d/csJJslD
| dylan604 wrote:
| good lord. that's cool, but wow would that be expensive. did
| you only use this on the exterior walls of the house? how
| much primer did it take to get the paint to match the rest of
| the walls? also, what about windows?
| swader999 wrote:
| I did it inside my bedroom, ceiling and all walls because
| we are fairly close to a cell tower. The rf meter I have
| went from 3000-5000 down to 7-10. I can't type the symbols
| in my phone for the units. Better sleep for sure since
| doing that a couple of years ago.
|
| Windows we used film, curtains shielded too. Two coats
| primer. Put copper stripts to ground as well on walls
| before paint. Didn't do floor so some rf gets in and out
| which is ok actually, you can create a focusing effect if
| you aren't careful about it.
| flemhans wrote:
| Do you sleep better because you're not on your phone so
| much? I've heard that you should avoid screens in bed.
| surfingdino wrote:
| Do I sense a future asbestos-like scandal brewing here?
| CyberDildonics wrote:
| What evidence are you basing that on?
| yomlica8 wrote:
| How well does this work? Always sounded to good to be true to
| me.
| orbital-decay wrote:
| The paint itself probably works well if it's conductive -
| it's just a simple Faraday shield. The problem is with
| testing. For example most Faraday pouches and bags turn out
| to be snake oil upon testing, as they let the signal out
| through some discontinuities, even though the mesh itself
| works perfectly and _most_ of the time you don 't have the
| signal.
| chaosbolt wrote:
| Tinfoil
| IshKebab wrote:
| I would start by not building your password out of giant metal
| letters.
| dinkleberg wrote:
| How else am I supposed to keep track of it?
| FirmwareBurner wrote:
| Ask the Amsish
| lawlessone wrote:
| i don't think being unaware protects you.
| beardyw wrote:
| Wow, can I fulfill me dream of living in a 1984 style dystopia?
___________________________________________________________________
(page generated 2023-09-11 22:00 UTC)