[HN Gopher] Covert Web-to-App Tracking via Localhost on Android
       ___________________________________________________________________
        
       Covert Web-to-App Tracking via Localhost on Android
        
       Author : sebastian_z
       Score  : 245 points
       Date   : 2025-06-03 12:12 UTC (10 hours ago)
        
 (HTM) web link (localmess.github.io)
 (TXT) w3m dump (localmess.github.io)
        
       | rvnx wrote:
       | Not surprising, it's legal, but only if you are a multi-billion
       | dollars company.
        
       | orbital-decay wrote:
       | Actual report: https://localmess.github.io/
       | 
       | >Google says it's investigating the abuse
       | 
       | That's a bit ironic, considering how they're using any side
       | channel they could lay their hands on (e.g. Wi-Fi AP names) to
       | track everyone. Basically every large app vendor with multiple
       | apps does something similar to circumvent OS restrictions as
       | well.
        
       | voidUpdate wrote:
       | I wish we could just ban advertising and tracking on the
       | internet. I feel like so much crap these days has come out of it,
       | all so that CEOs can afford an extra yacht
        
         | crowcroft wrote:
         | The question is how do you ban it, and then how do you prove
         | that people are breaking those rules?
        
           | fsflover wrote:
           | https://news.ycombinator.com/item?id=43595269
        
             | crowcroft wrote:
             | I like the idea, but where do you draw the line on what
             | advertising is.
             | 
             | Is affiliate marketing still allowed? Are influencers
             | allowed to take payment? Can people be a spokesperson for a
             | company? Can newspapers run commentary about businesses?
             | Can companies pay to be vendors at a conference?
             | 
             | No matter where you end up drawing the line you're just
             | shifting the problems somewhere else. Look at the amount of
             | money Meta and Google make, the incentive is just too
             | large.
        
           | voidUpdate wrote:
           | I know. It's wishful thinking that will never become a
           | reality. I pray for a solarpunk future in the same way
        
           | numpad0 wrote:
           | By defining the $thing, banning the $thing per definition by
           | law, and then tasking FBI-like organization enforce the law?
           | It won't completely go away but it will subside, like how
           | gambling on Internet is divided binary and confined into
           | lootbox games without cashing features and straight up scam
           | underground casinos.
           | 
           | Personally I think we should start from separating good old
           | ads(that existed before _I_ was 15) and Internet  "ads". The
           | old ads were still somewhat heavily targeted, but less than
           | it is now. There probably would be an agreeable line up to
           | which level advertisement efforts can be perverted.
        
             | the_sleaze_ wrote:
             | Yes - although I disagree on one point.
             | 
             | All we need to do is define the $thing and mandate that
             | lawsuits can be effective.
             | 
             | No agency enforces that potato chips need to fill up 92% of
             | the bag or whatever, or that McDonalds cannot show pictures
             | of apple fritters with more apples than they actually come
             | with (this happened).
             | 
             | You just incentivize a cottage industry of legal that can
             | squeeze a profit out of suing peanut butter companies for
             | labelling incorrectly, or advertising dishonestly and it
             | sort of takes care of itself.
        
             | crowcroft wrote:
             | I mean the comparison of 'old' ads vs new ads is
             | interesting in itself, old ads already abide by far more
             | regulation and are far more auditable. Simply bringing
             | digital ads in line would be a big step forward.
             | 
             | Some examples:
             | 
             | In most countries it's illegal to 'target minors' and
             | there's restrictions on what ads can run on after school
             | hours. Meta has always allowed age targeting down to 13 and
             | has no time of day restrictions.
             | 
             | In parts of New Zealand you can't advertise alcohol between
             | 10PM and 9AM... unless you do it on Meta or Google.
             | 
             | Most countries have regulation about promoting casinos (or
             | the inability to) unless they're digital casinos being
             | promoted in digital ads.
             | 
             | Or just look at the deepfake finance and crypto ads that
             | run on Meta and X. Meta requires 24 strikes against an
             | advertiser before they pull them down, if a TV network ran
             | just one ad like that it would be a scandal.
             | 
             | Audit-ability is the biggest issue imo. If a TV ad runs we
             | can all see it at the same time and know it ran. That is
             | simply impossible with digital ads, and even when Meta
             | releases some tools for auditing the caveat is that you
             | still have to trust what they're releasing. Similarly with
             | data protection there's no way to truly audit what they're
             | doing unless you install government agencies in the
             | companies to provide oversight, and I don't see how you
             | could really make that work.
        
               | voidUpdate wrote:
               | It would be nice if they also couldn't target us with
               | more information than what we consent to give them. Like,
               | fine, if you want to target facebook ads at people using
               | details they've filled in, I can see that being
               | acceptable, but trying to scrape every single byte of
               | data about us and using that to throw targeted ads at us
               | feels icky.
               | 
               | Better moderation of crappy AI-generated image ads that
               | are just scamming you would be nice as well.
        
           | lucianbr wrote:
           | I think the main problem is lots of money are made from it,
           | and money influences politics hugely. The technical
           | difficulties are low on the list of reasons this is not
           | happening.
        
         | pseudocomposer wrote:
         | The deprecation of third-party cookies, that _all browsers were
         | at one point on track to implement_ , was pretty much the most
         | realistic first step to that. Which is why Google killed it
         | last year by leveraging their control over Chrome.
         | 
         | While not technically a crime, it was a disgusting, unethical
         | market manipulation move that never really got the public
         | outrage it deserved.
         | 
         | Google execs' initial support for it was also telling:
         | leadership at Google must literally thought they would find
         | another way to stay as profitable as they are without third-
         | party cookies. Put another way: Google leadership didn't
         | understand cookies as well as someone who's taken a single
         | undergrad web dev class. (Or they were lying all along, and
         | always planned to "renege" on third-party cookie deprecation.)
        
           | crawsome wrote:
           | Insidiously calling it "Privacy sandbox", and now setting
           | everything opt-in every time I login to Chrome is really not
           | Googly.
        
           | IggleSniggle wrote:
           | I don't think that's quite what happened. Google got in anti-
           | trust trouble because they have an unfair advantage in user-
           | tracking, given logged in Chrome accounts. Removing third-
           | party cookies hurts other privacy-invading companies without
           | substantially affecting Google. It was still somewhat on
           | track to be removed from Chrome until they lost their
           | antitrust battle, and Chrome was required to be spun off.
           | With Chrome's new future, and Google's new legal constraints,
           | there's less incentive to try and make Privacy Sandbox work.
           | At least, that was my understanding; I didn't follow it all
           | that closely.
        
           | skybrian wrote:
           | Most commenters on Hacker News hated Google's plan and hoped
           | it would fail. Were they wrong?
           | 
           | It seems like damned-if-you-do, damned-if-you-don't.
        
             | threecheese wrote:
             | That stemmed from "dammit Google now every SaaS developer
             | has to work nights to meet your arbitrary deadline"; here
             | we're caring more about the impact as consumers. It's ok to
             | think about things in two ways.
             | 
             | source: a developer who actually did have to do this (and
             | did it, and now didn't have to, but it's done)
        
         | Workaccount2 wrote:
         | >all so that CEOs can afford an extra yacht
         | 
         | ...and so consumers can use services/products without having to
         | fork over money.
         | 
         | People _love_ the ad-model. Given the option to pay or use the
         | "ad-supported" option, the ad-supported one wins 10 to 1. This
         | means in many cases it doesn't even make sense to have a paid
         | option, because the ad option is just so much more popular.
         | 
         | As bad as crypto is, with all the negative things attached to
         | it, BAT was probably one of the smartest things to be invented.
         | A browser token that automatically dispenses micropayments to
         | websites you visit. Forget all the details to get snagged on,
         | the basic premise is solid: Pay for what you use. You become
         | the customer, not the advertisers.
         | 
         | Also a note about ad-blocking - it only makes the problem
         | worse. It is not a "stick it to the man" protest. You protest
         | things by boycotting them, or paying their competitors, not by
         | using them without compensating them.
        
           | rkomorn wrote:
           | I really liked the concept of BAT but the reality left me
           | wanting.
           | 
           | Things like "we'll hang on to the tokens of sites that don't
           | use BAT yet for them until they join" gave negative vibes.
           | 
           | It all felt a little underbaked. I swing back to Brave once
           | in a blue moon and then remember I've got at least $20's
           | worth of BAT lost forever somewhere.
        
             | Workaccount2 wrote:
             | I'm not a big fan of it or anything, it's just the only
             | crypto I know that was targeting that idea.
             | 
             | I'd love if there was another one that was totally open and
             | just a browser extension away. But I do not think it would
             | ever get off the ground because...
             | 
             | People love the ad model and hate paying for things.
        
           | SecretDreams wrote:
           | Yes, we need ads for a free internet, today. And, as a
           | result, we also have our privacy eroded - eroded in ways we
           | may not care about today, but will probably regret tomorrow.
           | 
           | If we must pay for the internet, give me an option to pay to
           | use it where I see no ads and my privacy is preserved. Let me
           | know what that cost is and I'll decide what I want to do.
           | 
           | Right now, the actual pricing is obscured so we just "accept"
           | that the internet in its current form is how it needs to be.
        
           | account42 wrote:
           | There is no such thing as a free lunch. Consumers on average
           | are forking over the money. Otherwise no one would pay for
           | advertising. And they are paying more than they would have
           | otherwise since this dystopian tracking apparatus isn't free
           | either.
        
         | fuzzfactor wrote:
         | This type of thing is pure greed, completely distinct from a
         | highly aggressive pursuit of far more lucrative opportunities
         | that average businessmen have been able to accomplish in the
         | extreme interest of their shareholders.
         | 
         | Those true leaders are the traditional examples who have shown
         | success over the centuries, without letting any greed
         | whatsoever become a dominant force, recognizing and moving in
         | the opposite direction from those driven by overblown self-
         | interest, who naturally have little else to offer. It can be
         | really disgraceful these days but people don't seem to care any
         | more.
         | 
         | That's one thing that made them _average_ businessmen though.
         | 
         | Now if you're below-average I understand, but most companies'
         | shareholders would be better off with a non-greedy CEO, who
         | outperforms by steering away from underhanded low-class
         | behavior instead.
         | 
         | Now if greed is the only thing on the table, and somebody like
         | a CEO or decision-making executive hammers away using his only
         | little tool with admirable perseverance long enough, it does
         | seem to have a likelihood of bringing in money that would not
         | have otherwise come in.
         | 
         | This can be leveraged too, by sometimes even greedier forces.
         | 
         | All you can do is laugh, those shareholders might be satisfied,
         | but just imagine what an _average_ person could do with that
         | kind of resources. It would put the greedy cretins to shame on
         | their own terms.
         | 
         | And if you could find an honest above-average CEO, woo hoo !
        
         | Hilift wrote:
         | Reddit has fairly extensive device fingerprinting. And they are
         | selling data for training AI models. It's only a matter of time
         | before there is some premium phone app that monetizes data that
         | otherwise isn't available/for sale.
        
       | lostmsu wrote:
       | This just reinforced the use of uMatrix. Governments should
       | mandate browser vendors to implement any standards gorhill might
       | come up with.
        
         | pabs3 wrote:
         | If only uMatrix was still developed/supported.
        
           | pmontra wrote:
           | It still works very well. I'm using it on both Linux and
           | Android. The UI is far better than its replacement inside
           | uBO.
        
             | fc417fc802 wrote:
             | The uBO functionality isn't a legitimate replacement. I
             | don't understand how that came to pass.
        
         | k4rli wrote:
         | Unfortunately in modern web uMatrix is just incredibly
         | annoying. Nearly every site breaks for various reasons and
         | often allowing everything in uMatrix still doesn't fix the
         | issue.
         | 
         | Card payments, especially with 3D secure that use iframes, are
         | one of the biggest problems. This often leads to creating new
         | order several times since allowing something + reloading loses
         | the entire flow.
         | 
         | Captchas are also massive pain, probably because they can't
         | fingerprint as well as normally?
         | 
         | Life after having disabled uMatrix completely has been better.
        
       | Xiol32 wrote:
       | Crap like this is why I haven't had the Facebook or Instagram
       | apps installed for years. I still have accounts, but I only visit
       | them via the browser.
        
         | codedokode wrote:
         | I am not going to register with FB because they now require a
         | 3D face scan to use it.
        
         | bravesoul2 wrote:
         | It just wants to make me bin my phone tbh. Thank God for RMS
         | and Linus that at least you can run GNU and Linux on a laptop
         | as there is little left outside the panopticon.
        
       | qwertox wrote:
       | "UPDATE: As of June 3rd 7:45 CEST, Meta/Facebook Pixel script is
       | no longer sending any packets or requests to localhost. The code
       | responsible for sending the _fbp cookie has been almost
       | completely removed."
       | 
       | I'm surprised they're allowed to listen on UDP ports, IIRC this
       | requires special permissions?
       | 
       | > The Meta (Facebook) Pixel JavaScript, when loaded in an Android
       | mobile web browser, transmits the first-party _fbp cookie using
       | WebRTC to UDP ports 12580-12585 to any app on the device that is
       | listening on those ports.
       | 
       | Borders on criminal behavior.
       | 
       | Apparently this was a European team of researchers, which would
       | mean that Meta very likely breached the GDPR and ePrivacy
       | Directive. Let's hope this gets very expensive for Meta.
        
         | fluidcruft wrote:
         | Nothing quite like an instant panicked coverup to confirm guilt
         | and intent.
         | 
         | Hopefully not too late to make it into the lawsuit. Assholes.
        
           | reaperducer wrote:
           | _Hopefully not too late to make it into the lawsuit.
           | Assholes._
           | 
           | I sure hope there's a lawsuit. Over the last ten years, I've
           | gotten over $2,000 in lawsuit settlement checks from Meta,
           | alone.
           | 
           | I have a savings account at one of my banks that I use just
           | for these settlement checks. Sometimes they're just $5.
           | Sometimes they're a lot more. I think the most I ever got was
           | around $500.
           | 
           | It's a little bit here, and a little bit there, but at the
           | rate it's going, in another five years, I'll be able to buy a
           | car with privacy violation money.
        
           | IncreasePosts wrote:
           | As someone who works for a similar large org, it's just as
           | likely that some low level programmer put it in without much
           | thought, and then this got surfaces to higher up people who
           | didn't know about it and told them to remove it immediately.
        
             | crtasm wrote:
             | It seems incredibly unlikely a low level programmer could
             | come up with this method then get the necessary code into
             | both the tracking pixel served to third party sites _and_
             | Meta 's android apps without some higher ups knowing about
             | it.
        
               | lesuorac wrote:
               | Or at the very least, a low level programmer not claiming
               | credit for it during performance reviews which are
               | reviewed by higher people.
        
         | paxys wrote:
         | These companies have demonstrated repeatedly that fines are
         | just the cost of doing business. Doesn't matter if you charge
         | them $1 million or $1 billion. They have still made
         | significantly more than that from the crime.
        
           | bauerd wrote:
           | The sum absolutely does matter. All you're saying is the
           | fines are too low
        
           | account42 wrote:
           | That's why fines should scale up geometrically with repeat
           | offenses.
        
           | maeil wrote:
           | That's.. quite the contradictory sentence.
        
         | reaperducer wrote:
         | _> The Meta (Facebook) Pixel JavaScript, when loaded in an
         | Android mobile web browser, transmits the first-party _fbp
         | cookie using WebRTC to UDP ports 12580-12585 to any app on the
         | device that is listening on those ports._
         | 
         | And people on HN dismiss those who choose to browse with
         | Javascript disabled.
         | 
         | There's a reason that the Javascript toggle is listed under the
         | Security tab on Safari.
        
           | account42 wrote:
           | Worse, people on HN _celebrate_ when websites add anti-bot
           | protection that prevent you from accessing the website
           | without JS.
        
       | pabs3 wrote:
       | I'm surprised browsers don't isolate each of the
       | localhost/localnet/internet networks from each other. Are there
       | any use-cases for allowing this?
        
         | matthberg wrote:
         | If I recall correctly Figma uses it to connect to the locally
         | installed app, and Discord definitely uses it to check if its
         | desktop app is installed by scanning ports (6463-6472).
         | 
         | I'm aware of two blockers for LAN intrusions from public
         | internet domains, uBlock Origin has a filter list called "Block
         | Outsider Intrusion into LAN" [0] under the "Privacy" filters,
         | and there's a cool Firefox extension called Port Authority
         | [1][2] that does pretty much the same thing yet more
         | specifically targeted and without the exclusions allowed by the
         | uBlock filterlist (stuff like Figma's use is allowed through,
         | as you can see in [0]). I've contributed some to Port
         | Authority, too :)
         | 
         | 0:
         | https://github.com/uBlockOrigin/uAssets/blob/master/filters/...
         | 
         | 1: https://addons.mozilla.org/firefox/addon/port-authority
         | 
         | 2: https://github.com/ACK-J/Port_Authority
        
           | bravesoul2 wrote:
           | There are surely other ways to achieve this. If you are
           | logged into an app and the site at tbe same time they can use
           | the server to communicate. Discord doesn't need to know if
           | the app is installed to work. That sounds sketchy.
        
             | Orphis wrote:
             | It's just a way to ensure you open the desired context on a
             | local Discord instance, not any instance that might be
             | logged in to your account. I have a few personal computers
             | logged in on Discord on the same account that could be
             | active at the same time for example.
        
           | pabs3 wrote:
           | The native messaging feature is a much better way to talk to
           | native apps, that should be used instead for modern browsers.
        
       | neuroticnews25 wrote:
       | To me it's weird that they're willing to misuse browser APIs so
       | blatantly for interprocess communication, when, as I understand
       | it, server-side correlation using a combination of IP, battery
       | level and screen dimensions probably already gets them 95% of the
       | surveillance capability.
        
         | dylan604 wrote:
         | Why is this weird to you instead of being "of course they are"
         | to you?
        
         | Retr0id wrote:
         | the invisible hand says they have to chase that last 5%, too
        
       | jeroenhd wrote:
       | A quite obvious attack mechanism, I'm surprised browsers
       | permitted this in the first place. I can't think of a reason to
       | STUN/TURN to localhost. Aside from localhost, trackers can also
       | use all other IP addresses available to the browser to bind their
       | apps/send traffic to.
       | 
       | Now that the mechanism is known (and widely implemented), one
       | could write an app to notify users about attempted tracking. All
       | you need to do is to open the listed UDP ports and send a
       | notification when UDP traffic comes in.
       | 
       | For shit and giggles I was pondering if it was possible to modify
       | Android to hand out a different, temporary IPv6 address to every
       | app and segment off any other interface that might be exposed
       | just because of shit like this (and use CLAT or some fallback
       | mechanism for IPv4 connectivity). I thought this stuff was just a
       | theoretical problem because it would be silly to be so blatant
       | about tracking, but Facebook proves me wrong once again.
       | 
       | I hope EU regulators take note and start fining the websites that
       | load these trackers without consent, but I suspect they won't
       | have the capacity to do it.
        
         | fc417fc802 wrote:
         | > hand out a different, temporary IPv6 address to every app and
         | segment off any other interface that might be expose
         | 
         | Yes, but (AFAIK) not out of the box (unless one of the security
         | focused ROMs already supports this). The kernel supports
         | network namespaces and there's plenty of documentation
         | available explaining how to make use of those. However I don't
         | know if typical android ROMs ship with the necessary tooling.
         | 
         | Approximately, you'd just need to patch the logic where zygote
         | changes the PID to also configure and switch to a network
         | namespace.
        
           | jeroenhd wrote:
           | I've looked into network namespaces a bit but from what I can
           | tell you need to do a lot of manual routing and other weird
           | stuff to actually make IPv6 addresses reachable through them.
           | 
           | In theory all you need to do is have zygote constrain the app
           | further with a network namespaces, and run a CLAT daemon for
           | legacy networks, but in practice I'm not sure if that
           | approach works well with 200 apps that each need their IPs
           | rotated regularly.
           | 
           | Plus, you'd need to reconfigure the sandbox when switching
           | between WiFi/5G/ethernet. Not impossible to overcome, but not
           | the weekend project I'd hoped it would be.
        
         | candiddevmike wrote:
         | > modify Android to hand out a different, temporary IPv6
         | address to every app
         | 
         | AFAIK this is on the Android roadmap and one of the key reasons
         | they don't want to support DHCPv6. They want each app to have
         | their own IP.
        
       | bix6 wrote:
       | What happened to all the hackers fighting for personal freedom
       | and privacy? Meta paycheck too tasty?
        
         | Agentus wrote:
         | at some point yah reach a cross road. either sellout and join
         | big brother or join the wandering homeless hordes on the
         | streets.
        
           | kstrauser wrote:
           | Eh. You can have a very comfortable career doing work that
           | still lets you look at yourself in the mirror. You don't
           | _have_ to choose to burn the world to pay the rent.
        
             | bix6 wrote:
             | I agree with you but I also don't. It's a privilege to have
             | the ability to choose which job you work.
        
               | kstrauser wrote:
               | Not in this case. If you're qualified to get a job at a
               | company who will pay you to sell out your neighbor,
               | you're qualified to get a job with a decent boss who'll
               | never ask you do to do this kind of thing, pays 90% as
               | much, and is still many times the national average
               | salary.
               | 
               | The alternatives are not doing evil vs starving. They're
               | getting paid well for doing evil, or getting paid well
               | for doing good or at least neutral.
        
               | bix6 wrote:
               | Ok you've convinced me!
        
         | kstrauser wrote:
         | We're still fighting the fight. Turns out shifty assholes also
         | figured out how to write code and get hired.
        
           | bix6 wrote:
           | Thank you for your service!
        
         | danaris wrote:
         | In the early days of the information revolution, when computers
         | were new and being nerdy was still seen (almost universally) as
         | a bad thing, a very high proportion of computer enthusiasts
         | were people already on the fringes of society, for one reason
         | or another. For a large number of them, hacking was a way to
         | express their preexisting antiestablishment tendencies. For a
         | lot of them, they were also your basic angsty adolescents and
         | young adults rebelling against The Man as soon as they found
         | any way to do so.
         | 
         | As time went on, computers became more mainstream, and lots
         | more people started using them as part of daily life. This
         | didn't mean that the number of antiestablishment computer users
         | or hackers went down--just that they were no longer nearly so
         | high a percentage of the total number of computer users.
         | 
         | So the answer to "what happened to all the hackers fighting for
         | personal freedom and privacy?" is kinda threefold:
         | 
         | 1) They never went away. They're still here, at places like the
         | EFF, fighting for our personal freedom and privacy. They're
         | just much less noticeable in a world where _everyone_ uses
         | computers...and where many more of the prominent institutions
         | actually know how to secure their networks.
         | 
         | 2) They grew up. Captain Crunch, the famous phreaker, is 82
         | this year. Steve Wozniak is 74. And while, sure, some people
         | reach that age and still maintain not merely a philosophy, but
         | a practice, of activism, it's much harder to keep up, and even
         | many of those whose principles do not change will shift to
         | methods that stay more within the system (eg, supporting
         | privacy legislation, or even running for office themselves).
         | 
         | 3) They went to jail, were "scared straight", or died. The most
         | prominent example of this group is, of course, Aaron Swartz,
         | but many hacktivists will have had run-ins with the law, and of
         | those many of them will have turned their back on the lifestyle
         | to save themselves (even Captain Crunch was arrested and
         | cooperated with the FBI).
        
           | bix6 wrote:
           | Thanks for your thoughts! How can we create more hackers? I
           | think the fear of punishment has really put a damper on
           | things but not sure how that can be avoided.
        
             | kstrauser wrote:
             | Hacking isn't about crime. It's about exploration. There
             | are lots of people showing "the youths" how interesting it
             | is to break a lock or go around it. Basically, any time you
             | can make a system do something fun, helpful, or interesting
             | that it wasn't intended to do, that's hacking. You can be
             | 100% law abiding with no fear of punishment and still get
             | the full experience.
        
         | paxys wrote:
         | Who do you think found the issue?
        
           | bix6 wrote:
           | Touche
        
       | GrantMoyer wrote:
       | Would an individual using this technique to collect information
       | from someone else's computer possibly face prosecution under the
       | Computer Fraud and Abuse act?
        
         | croes wrote:
         | Yes
        
         | paxys wrote:
         | People have been prosecuted under that act for clicking "view
         | source" on their web browser. The crime itself is irrelevant.
         | It's more about who you are/what connections you have/who you
         | piss off.
        
         | gruez wrote:
         | This only works if you control the code on both sides (ie. on
         | the website being visited and an app running on the phone).
         | It's not some sort of magic hack that allows you to exfiltrate
         | arbitrary browser history. Therefore it's unclear how it can be
         | construed as "hacking" in any meaningful way. As bad non-
         | consensual tracking done by google/meta/whatever are, it's not
         | covered under CFAA.
        
           | GrantMoyer wrote:
           | I agree it's not hacking, but the Computer Fraud and Abuse
           | act seems to have a pretty broad definition of computer fraud
           | and abuse. In particular, the technique seems like it might
           | (emphasis mine) "knowingly and with intent to defraud,
           | accesses a protected computer without authorization, or
           | _exceeds authorized access_ , and by means of such conduct
           | furthers the intended fraud and obtains anything of value
           | ...". Would the other person have a reasonable belief that
           | they didn't authorize access to information which their OS
           | attempts to prevent access to?
           | 
           | I'm not a lawyer, so my question is genuine.
        
           | threecheese wrote:
           | The yandex one uses client/browser-side code to exfiltrate;
           | it's within the realm of possibility to abuse this, given a
           | user visits a site under your control.
           | 
           | On the FB side, I can see a malicious user potentially
           | poisoning a target site visitors's ad profile or even social
           | media algorithm with crafted cookies. Fill their feed with
           | diaper ads or something.
        
       | merek wrote:
       | This is the overall process used by Meta as I understand it,
       | taken from https://localmess.github.io/:
       | 
       | 1. User logged into FB or IG app. The app runs in background, and
       | listens for incoming traffic on specific ports.
       | 
       | 2. User visits website on the phone's browser, say something-
       | embarassing.com, which happens to have a Meta Pixel embedded.
       | From the article, Meta Pixel is embedded on over 5.8 million
       | websites. Even in In-Cognito mode, they will still get tracked.
       | 
       | 3. Website might ask for user's consent depending on location.
       | The article doesn't elaborate, presumably this is the cookie
       | banner that many people automatically accept to get on with their
       | browsing?
       | 
       | 4. > The Meta Pixel script sends the _fbp cookie (containing
       | browsing info) to the native Instagram or Facebook app via WebRTC
       | (STUN) SDP Munging.
       | 
       | You won't see this in your browser's dev tools.
       | 
       | 5. Through the logged-in app, Meta can now associate the
       | "anonymous" browser activity with the logged-in user. The app
       | relays _fbp info and user id info to Meta's servers.
       | 
       | Also noteworthy:
       | 
       | > This web-to-app ID sharing method bypasses typical privacy
       | protections such as clearing cookies, Incognito Mode and
       | Android's permission controls. Worse, it opens the door for
       | potentially malicious apps eavesdropping on users' web activity.
       | 
       | > On or around May 17th, Meta Pixel added a new method to their
       | script that sends the _fbp cookie using WebRTC TURN instead of
       | STUN. The new TURN method avoids SDP Munging, which Chrome
       | developers publicly announced to disable following our
       | disclosure. As of June 2, 2025, we have not observed the Facebook
       | or Instagram applications actively listening on these new ports.
        
         | fluidcruft wrote:
         | Not totally following but it sounds like you are saying one of
         | the things they have been doing involves abusing mandated GDPR
         | cookie notices to secretly track people?
        
           | scott_w wrote:
           | Which, on the face of it, sounds like a violation of the
           | GDPR...
        
             | fluidcruft wrote:
             | The intent of these laws is just so obtuse and unclear! And
             | beyond that complying is technically impossible to
             | implement but you could only understand that if you were a
             | rocket scientist PhD computer science wizkid making $$$$k
             | in California which isn't that much in such a high cost of
             | living area donchaknow. /sardonic
        
           | gruez wrote:
           | >abusing mandated GDPR cookie notices to secretly track
           | people?
           | 
           | How does that even work? What can GDPR cookie notices can do
           | that the typical tracker can't do?
        
           | threecheese wrote:
           | Yes? The cookie in question is First Party, which means
           | you've consented to permitting only that party to track you
           | using it, and not permitting its use for wider behavioral
           | tracking across websites.
           | 
           | However, the locally hosted FB/Yandex listener receives all
           | of these first party cookies, from all parties, and the OPs
           | implication is (I think) that now these non-correlateable-by-
           | consent first party cookies can be or are being used to track
           | you across all sites that use them.
        
             | threecheese wrote:
             | Not only did you only consent to the one party using it,
             | but the browser has robust protections in place to ensure
             | that these cookies are only usable by that party. This
             | "hack" gets around the restriction completely, leveraging a
             | local service to aggregate all the cookies across sites.
        
         | codedokode wrote:
         | So main application for WebRTC is de-anonymisation of users
         | (for example getting their local IP address). Why it is not
         | hidden behind permission I don't understand.
        
           | afavour wrote:
           | The main application for WebRTC is peer to peer data
           | transfer.
           | 
           | I think you can make the argument that it should be behind a
           | permission prompt these days but it's difficult. What would
           | the permission prompt actually say, in easy to understand
           | layman's terms? "This web site would like to transfer data
           | from your computer to another computer in a way that could
           | potentially identify you"? How many users are going to be
           | able to make an informed choice after reading that?
        
             | codedokode wrote:
             | The website wants to connect to another computer|another
             | app on your computer.
             | 
             | Most users probably will click "No" and this is a good
             | choice.
        
               | afavour wrote:
               | But that says nothing about the danger of identifying
               | you.
               | 
               | > Most users probably will click "No"
               | 
               | Strong disagree. When I'm loading google.com is my
               | computer not connecting to another computer? From a
               | layman's perspective this is the basis of the internet
               | doing what it does. Not to mention, the vast majority of
               | users say yes to pretty much any permission prompt you
               | put in front of them.
        
               | gruez wrote:
               | >The website wants to connect to another computer|another
               | app on your computer.
               | 
               | "website wants to connect to another computer" basically
               | describes all websites. Do you really expect the average
               | user to understand the difference? The exploit is also
               | non-trivial either. SDP and TURN aren't privacy risks in
               | and of themselves. They only pose risks when the server
               | is set to localhost and with a cooperating app.
        
             | deepsun wrote:
             | Let it show "Use WebRTC?".
             | 
             | If users don't understand, they click whatever. If the
             | website really needs it to operate, it will explain why
             | before requesting, just like apps do now.
             | 
             | Always aim for a little more knowledgeable users than you
             | think they are.
        
               | afavour wrote:
               | That feels pretty useless. You might as well do what
               | happens today: enable it by default and allow
               | knowledgable power users to disable it. If it's disabled,
               | show a message to the user explaining why it's needed.
        
               | deepsun wrote:
               | Today there's no way to disable it, I searched through my
               | Firefox Mobile settings. So I'd say it's for very "power"
               | users.
               | 
               | And why enable it by default, why not disable by default?
               | 
               | Also, sibling comments say iOS is already asking for the
               | permission, why not just copy it?
        
               | btown wrote:
               | And specifically, if you're on something-sensitive.com in
               | a private browsing session, it would give you the choice
               | of giving _no_ optional permissions. That choice is
               | better than no choice at all, especially in a world where
               | Meta can be subpoenaed for this tracking data by actors
               | who may be acting unconstitutionally without sufficient
               | oversight.
        
             | account42 wrote:
             | TFA list tens of thousands of websites using WebRTC for
             | deanonymization. How many websites using it for P2P data
             | transfer can you list?
        
             | mindslight wrote:
             | Browser functionality needs a hard segmentation into
             | disparate categories like "pages" and "apps". For example,
             | _Pages_ that you 're merely intending to view don't need
             | WebRTC (or really any sort of network access beyond the
             | originating site, and even this is questionable). And you'd
             | only give something _App_ functionality if it was from a
             | trustable source and the intent was to use it as general
             | software. This would go a long way to solving the other
             | fingerprinting security vulnerabilities, because _Pages_
             | don 't need to be using functionality like Canvas, USB,
             | etc.
        
           | miloignis wrote:
           | The existing killer app for WebRTC is video chat without
           | installing an app, which is huge.
           | 
           | Other P2P uses are very cool and interesting as well -
           | abusing it for fingerprinting is just that, abusing a user-
           | positive feature and twisting it for identification, just
           | like a million other browser features.
        
             | account42 wrote:
             | You mean just like a million other "user-positive" browser
             | features pushed by the biggest tracking company there is.
        
         | consumer451 wrote:
         | > something-embarassing.com,
         | 
         | Depending on the country that you or your family lives in, this
         | could be far worse than embarrassment.
        
       | hulitu wrote:
       | > Meta and Yandex are de-anonymizing Android users' web browsing
       | identifiers
       | 
       | Thank god that Microsoft and Google don't do this. Oh, wait... /s
        
       | matthberg wrote:
       | A comment I wrote in another HN thread [0] covering this issue:
       | 
       | Web apps talking to LAN resources is an attack vector which is
       | surprisingly still left wide open by browsers these days. uBlock
       | Origin has a filter list that prevents this called "Block
       | Outsider Intrusion into LAN" under the "Privacy" filters [1], but
       | it isn't enabled on a fresh install, it has to be opted into
       | explicitly. It also has some built-in exemptions (visible in [1])
       | for domains like `figma.com` or `pcsupport.lenovo.com`.
       | 
       | There are some semi-legitimate uses, like Discord using it to
       | check if the app is installed by scanning some high-number ports
       | (6463-6472), but mainly it's used for fingerprinting by malicious
       | actors like shown in the article.
       | 
       | Ebay for example uses port-scanning via a LexisNexis script for
       | fingerprinting (they did in 2020 at least, unsure if they still
       | do), allegedly for fraud prevention reasons [2].
       | 
       | I've contributed some to a cool Firefox extension called Port
       | Authority [3][4] that's explicitly for blocking LAN intruding web
       | requests that shows the portscan attempts it blocks. You can get
       | practically the same results from just the uBlock Origin filter
       | list, but I find it interesting to see blocked attempts at a more
       | granular level too.
       | 
       | That said, both uBlock and Port Authority use WebExtensions'
       | `webRequest` [5] API for filtering HTTP[S]/WS[S] requests. I'm
       | unsure as to how the arcane webRTC tricks mentioned specifically
       | relate to requests exposed to this API; it's possible they might
       | circumvent the reach of available WebExtensions blocking methods,
       | which wouldn't be good.
       | 
       | 0: https://news.ycombinator.com/item?id=44170099
       | 
       | 1:
       | https://github.com/uBlockOrigin/uAssets/blob/master/filters/...
       | 
       | 2: https://nullsweep.com/why-is-this-website-port-scanning-me/
       | 
       | 3: https://addons.mozilla.org/firefox/addon/port-authority
       | 
       | 4: https://github.com/ACK-J/Port_Authority
       | 
       | 5: https://developer.mozilla.org/en-US/docs/Mozilla/Add-
       | ons/Web...
        
         | JimDabell wrote:
         | There is a specification for blocking this:
         | 
         | https://wicg.github.io/private-network-access/
         | 
         | It gained support from WebKit:
         | 
         | https://github.com/WebKit/standards-positions/issues/163
         | 
         | ...and Mozilla:
         | 
         | https://github.com/mozilla/standards-positions/issues/143
         | 
         | ...and it was trialled in Blink:
         | 
         | https://developer.chrome.com/blog/private-network-access-upd...
         | 
         | Unfortunately, it's now on hold due to compatibility problems:
         | 
         | https://developer.chrome.com/blog/pna-on-hold
        
           | matthberg wrote:
           | Yep! Unfortunately its main method (as far as I remember from
           | when I first read the proposal at least, it may do more) is
           | adding preflight requests and headers to opt-in, which works
           | for most cases yet doesn't block behind-the-lines
           | collaborating apps like mentioned in the main article. If
           | there's a listening app (like Meta was caught doing) that's
           | expecting the requests, this doesn't do much to protect you.
           | 
           | EDIT: Looks like it does mention integrating into the
           | permissions system [0], I guess I missed that. Glad they
           | covered that consideration, then!
           | 
           | 0: https://wicg.github.io/private-network-
           | access/#integration-p...
        
           | bakkoting wrote:
           | Both Firefox [0] and Chrome [1] are working on successors
           | which rely on permissions prompts instead of preflight
           | requests.
           | 
           | [0] https://groups.google.com/a/mozilla.org/g/dev-
           | platform/c/B8o...
           | 
           | [1] https://groups.google.com/a/chromium.org/g/blink-
           | dev/c/CDy8L...
        
         | account42 wrote:
         | > There are some semi-legitimate uses, like Discord using it to
         | check if the app is installed by scanning some high-number
         | ports (6463-6472)
         | 
         | I would not consider this a legitimate use. Websites have no
         | business knowing what apps you have installed.
        
           | robin_reala wrote:
           | Zoom got busted for something similar five years ago now:
           | https://www.zdnet.com/article/zoom-defends-use-of-local-
           | web-...
        
           | matthberg wrote:
           | I agree, yet at least you can kind of see where they're
           | coming from.
           | 
           | I guess a better example would be the automatic hardware
           | detection Lenovo Support offers [0] by pinging a local app
           | (with some clear confirmation dialogs first). Asus seems to
           | do the same thing.
           | 
           | uBlock Origin has a fair few explicit exceptions made [1] for
           | cases like those (and other reasons) in their filter list to
           | avoid breakages (notably Intel domains, the official
           | Judiciary of Germany [2] (???), `figma.com`,
           | `foldingathome.org`, etc).
           | 
           | 0: https://pcsupport.lenovo.com/
           | 
           | 1: https://github.com/uBlockOrigin/uAssets/blob/master/filter
           | s/...
           | 
           | 2: https://github.com/uBlockOrigin/uAssets/issues/23388 and
           | https://www.bundesjustizamt.de/EN/Home/Home_node.html
           | (they're trying to talk to a local identity verification app
           | seems like, yet I find it quite funny)
        
             | mschuster91 wrote:
             | > the official Judiciary of Germany [2] (???)
             | 
             | That's the e-ID function of our personal ID cards (notably,
             | NOT the passports). The user flow is:
             | 
             | 1. a client (e.g. the Deutsche Rentenversicherung,
             | Deutschland-ID, Bayern-ID, municipal authorities and a few
             | private sector services as well) wishes to get
             | cryptographically authenticated data about a person (name
             | and address).
             | 
             | 2. the web service redirects to Keycloak or another IDP
             | solution
             | 
             | 3. the IDP solution calls the localhost port with some
             | details on what exactly is requested, what public key of
             | the service is used, and a matching certificate signed by
             | the Ministry of Interior.
             | 
             | 4. The locally installed application ("AusweisApp") now
             | opens and displays these details to the user. When the user
             | wishes to proceed, the user clicks on a "proceed" button,
             | and is then prompted to either insert the ID card into a
             | NFC reader attached to the computer or a smartphone in the
             | same network as the computer that also has the AusweisApp
             | attached.
             | 
             | 5. The ID card's chip verifies the certificate as well and
             | asks for a PIN from the user
             | 
             | 6. the user enters the PIN
             | 
             | 7. the ID card chip now returns the data stored on it
             | 
             | 8. the AusweisApp submits an encrypted payload back to the
             | calling IDP
             | 
             | 9. the IDP decrypts this data using its private key and
             | redirects back to the actual application.
             | 
             | There is a bunch of cryptography additionally layered in
             | the process that establishes a secure tunnel, but it's too
             | complex to explain here.
             | 
             | In the end, it's a highly secure solution that makes sure
             | that _only_ with the right configuration and conditions
             | being met the ID card actually responds with sensitive
             | information - unlike, say, the Croatian ID card that will
             | go as far as to deliver the picture on the card in digital
             | form to anyone tapping your ID card on their phone. And
             | that 's also why it's impossible to implement in any other
             | way - maaaaybe WebUSB but you'd need to ship an entire
             | PC/SC stack and I'm not sure if WebUSB allows cleaving an
             | USB device that already has a driver attached.
             | 
             | In addition, the ID card and the passport also contains an
             | ICAO compliant method of obtaining the data in the MRZ, but
             | I haven't read through the specs of _that_ enough to
             | actually implement this.
        
         | account42 wrote:
         | IMO browsers should not just block the request but block the
         | whole website with one of those scary giant red banners if
         | something like this is attempted. If all websites get for
         | trying to work around privacy protections is that their
         | attempts might not succeed then there is little incentive not
         | to try.
        
         | xrisk wrote:
         | Your DNS server not resolving to localhost may also serve as an
         | additional line of defense.
        
           | h43z wrote:
           | What does this have to do with the issue here? A website can
           | just connect to 127.0.0.1 , no DNS needed.
           | 
           | I think what you are thinking of are dns rebinding attacks.
        
       | kriro wrote:
       | The EU should set some record breaking fines for this.
       | 
       | Maybe it's time to invent a tax that starts at 0% and goes up
       | 1-X% every time your hand is cought in the cookie jar. And add a
       | corresponding website where you can clearly see all violations by
       | company.
        
         | like_any_other wrote:
         | There should _also_ be fines, but individuals have gone to jail
         | for less.
        
         | Hilift wrote:
         | Meta makes $70 billion net per year, after fines.
        
       | bravesoul2 wrote:
       | So Meta apps are spyware. And Zuck agains has got his finger in
       | his mouth and a cat on his lap.
        
         | dylan604 wrote:
         | All Meta software is spyware. Whether it's an app or a website,
         | they are only in existence for you to be pacified to spend as
         | much time on them as possible so they can hoover up your data.
         | If those apps/websites provide you with anything useful, it is
         | just as a ruse to get more data from you.
        
       | dylan604 wrote:
       | *: Meta Pixel script was last seen sending via HTTP in Oct 2024,
       | but Facebook and Instagram apps still listen on this port today.
       | They also listen on port 12388 for HTTP, but we have not found
       | any script sending to 12388.         **: Meta Pixel script sends
       | to these ports, but Meta apps do not listen on them (yet?). We
       | speculate that this behavior could be due to slow/gradual app
       | rollout.
       | 
       | So, could some other app send data to these ports with a fake
       | message? I'm asking for a friend that likes to do things for
       | science.
        
         | fshafique wrote:
         | Two ways to f#ck with these trackers - either send them nothing
         | back, or flood them with lots of fake data.
         | 
         | Somebody also needs to come up with a way to peer to peer share
         | advertiser tracking cookies.
        
       | paxys wrote:
       | All apps + the web browser being able to communicate freely over
       | a shared localhost interface is such a glaring security hole that
       | I'm surprised both iOS and Android allow it. What even is a
       | legitimate use case for an app starting a local web server?
        
         | dylan604 wrote:
         | Which begs the question why is this specific to Android? Why
         | would Meta/Yandex not be doing this on iOS, or why did this
         | study not report on iOS?
        
           | mig39 wrote:
           | Doesn't iOS prompt you to give apps permission to connect to
           | your local network? "App would like to find and connect to
           | devices on your local network" or something along those
           | lines. I always hit the "no thanks" button.
        
             | paxys wrote:
             | In this case it's the web browser connecting to the
             | network, so the permission is irrelevant.
        
         | JimDabell wrote:
         | > What even is a legitimate use case for an app starting a
         | local web server?
         | 
         | There are apps on iOS that act as shared drives that you can
         | attach via WebDAV. This requires listening on a port for
         | inbound WebDAV (HTTP) requests.
        
       | like_any_other wrote:
       | A commenter mentioned [1] that major Russian apps now all ask for
       | permission to read a unique device ID to deanonymize users. The
       | people that stopped Intel from adding such an ID to their CPUs
       | had perfect foresight [2] (too bad later Intel added it anyway).
       | But then it's not hard to guess that if you include a feature
       | whose purpose is to attack the user, it will be used to attack
       | the user.
       | 
       | [1] https://arstechnica.com/security/2025/06/meta-and-yandex-
       | are...
       | 
       | [2]
       | https://en.wikipedia.org/wiki/Pentium_III#Controversy_about_...
        
         | gruez wrote:
         | >A commenter mentioned [1] that major Russian apps now all ask
         | for permission to read a unique device ID to deanonymize users.
         | 
         | To be fair it's not really limited to Russian apps. Many
         | popular apps on play store have it as well:
         | 
         | https://play.google.com/store/apps/details?id=org.telegram.m...
         | 
         | https://play.google.com/store/apps/details?id=com.microsoft....
         | 
         | https://play.google.com/store/apps/details?id=com.pinterest&...
        
       | lachlan_gray wrote:
       | Is there a similar thing on iOS? I always wonder when a random
       | app asks to "find devices on my network"
        
         | JimDabell wrote:
         | This is answered on the page.
        
         | pacifika wrote:
         | > That said, similar data sharing between iOS browsers and
         | native apps is technically possible.
        
         | cosmic_cheese wrote:
         | Possible, but potentially not as practical due to the iOS'
         | restrictive background process model. There, background tasks
         | are generally expected to quickly do whatever it is they need
         | to and exit and generally can't run indefinitely. Periodic
         | tasks are scheduled by the OS, with scheduling requests from
         | apps being more likely to be honored if their processes are
         | well-behaved (quick, low resource, don't crash, and don't run
         | too frequently) with badly-behaved processes getting run less
         | often.
         | 
         | Apps that keep themselves open by reporting that they're
         | playing audio might be able to work around this, but it'd still
         | be spotty since users frequently play media which would
         | suspended those backgrounded apps and eventually bump them out
         | of memory.
        
         | cluckindan wrote:
         | It's probably easier to buy that data directly from Apple.
         | 
         | Google's core business is built on tracking data, so they would
         | be reluctant to sell, necessitating covert collection.
        
       | bravesoul2 wrote:
       | Can this cross profiles? That would be a big security issue for
       | corps.
       | 
       | Quick test and if I serve on 8080 on the Userland app it can be
       | accessed from both profiles. So probably yes.
       | 
       | This means an infected app on your personal profile could
       | exchange data with a site visited from a second profile.
        
         | lxgr wrote:
         | Only if that site specifically communicates with an
         | (unauthenticated) service bound to a local port though, right?
        
           | btown wrote:
           | Which, per the OP, the site would be doing by merely
           | including the Meta pixel, which practically every e-commerce
           | and news site does to track its campaigns and organic
           | traffic.
           | 
           | The takeaway is that for all intents and purposes, anything
           | you did in a private session or secondary profile on an
           | Android device with any Meta app installed, was fully
           | connected to your identity in that app for an unknown amount
           | of time. And even with the tracking code deactivated, cookies
           | may still persist on those secondary profiles that still
           | allow for linking future activity.
        
             | lxgr wrote:
             | Yes, but if the concern is not mixing business and personal
             | compartment of the phone, business sites would hopefully
             | not embed a Meta tracking pixel.
             | 
             | > The takeaway is that for all intents and purposes,
             | anything you did in a private session or secondary profile
             | on an Android device with any Meta app installed, was fully
             | connected to your identity
             | 
             | Definitely, and that's a huge problem. I just don't think
             | Android business profiles are a particular concern here;
             | leaking app state to random websites in _any_ profile is
             | the problem.
             | 
             | Or do Android "business profiles" also include browser
             | sessions? Then this would be indeed a cross-compartment
             | leak. I'm not too familiar with Android's compartment
             | model; iOS unfortunately doesn't offer sandboxing between
             | environments that way.
        
               | d4mi3n wrote:
               | While I agree with your reasoning, in my experience any
               | statement where I prepend "hopefully" usually ends up
               | being the worst possible interpretation in practice.
        
               | lxgr wrote:
               | What I mean is: If a corporate internal website regularly
               | connects to unauthenticated local ports and _leaks
               | sensitive data out_ , that's fully on them.
               | 
               | If they are trying to fingerprint the "private
               | compartment" of a BYOB device, that seems roughly as bad
               | as a non-corporate side doing the same.
        
               | d4mi3n wrote:
               | 100% agree, and fingerprinting BYOB devices would be
               | problematic in a lot of ways.
               | 
               | I'm generally against BYOD programs. They're convenient
               | but usually come from a place of allowing employees
               | access to things without the willingness to take on the
               | cost (both in corp devices and inconvenience of a second
               | phone/tablet/whatever) to run them with a high level of
               | assurance.
               | 
               | Much better in my opinion to use something like PagerDuty
               | or text/push notifications to prompt folks to check a
               | corp device if they have alerts/new emails/whatever.
        
               | bravesoul2 wrote:
               | You can easily click a link e.g. to a blog post on Chrome
               | inside your profile.
               | 
               | E.g. a Jira ticket links to a post on how to do something
               | concurrency related in Python.
               | 
               | I get your point thought that maybe this is no worse than
               | if they visit the site on the personal side.
               | 
               | However I wouldn't trust out lack of imagination on how
               | to exploit this to be happy about the security gap!
        
               | glennpratt wrote:
               | > do Android "business profiles" also include browser
               | sessions
               | 
               | I believe that is typical.
               | 
               | My business profile has it's own instance of Chrome.
               | Mostly used for internal and external sites that require
               | corporate SSO or client certificates. Of course it could
               | be used to browse anything.
        
       | lgats wrote:
       | I built a little lan tool https://router.fyi that tries to get
       | LAN data for a sort of online-nmap. depending on your browser,
       | it's sometimes capable of finding wifi printers and a couple
       | other smart home devices i've manually added.
        
       | barbazoo wrote:
       | Probably hard to do for many but the solution seems be not to
       | have their apps installed. It's crazy to me that people tolerate
       | FB et al on their devices where you have absolutely no control
       | over what they're doing.
        
         | threecheese wrote:
         | I agree wrt Facebook, but there's a long tail of useful apps-
         | that-should-be-websites; 1 click for an app versus 45 seconds
         | searching through tabs and re-logging in (etc) can be
         | meaningful, especially when there are fifty of them.
         | 
         | My healthcare provider recently yanked the mobile version of
         | their portal website, and forces users to download their app.
         | Personally, I see the security angle, but still feel like it's
         | a punch in the face and so I just went back to paper billing
         | and using a PC for healthcare stuff. More of this is coming, I
         | suspect.
        
         | Hilift wrote:
         | Reddit has fairly intense device fingerprinting. And they sell
         | data for AI training.
        
       | username135 wrote:
       | Simple question: would disabling apps from running in the
       | background prevent this? Or, more simply, not staying logged into
       | an app on your phone?
        
       | robin_reala wrote:
       | Can you imagine the mental hoops you'd need to jump through as a
       | developer to persuade yourself that this is a valid thing to
       | implement?
        
         | fanatic2pope wrote:
         | My experience is that most developers just do as they are told.
        
           | robin_reala wrote:
           | Another reason why AI is so fascinatingly horrible: it'll
           | never question the moral impact of what you're trying to do.
        
         | ambicapter wrote:
         | Not many? You've never met a developer with a god complex?
        
         | edoceo wrote:
         | Get paid - it's one hoop.
        
         | kube-system wrote:
         | Zero. People who work on ad-tech build ad-tech all day long,
         | that's the entire job.
         | 
         | Seriously, why do you think all of the unquestionable things
         | humanity has built have been built? It's because it's all just
         | part of the job, for somebody.
         | 
         | People working at ad-tech question the things they're building
         | just like the people at McDonalds flipping a burger are
         | questioning the cholesterol levels of their customers. They're
         | not.
        
         | dylan604 wrote:
         | I mean, it is kind of a cool work around. There's a lot of
         | motivation in telling someone they can't do something where
         | "hide and watch" is a pretty typical response. The creative
         | thinking that comes up with ideas like this is not something to
         | discourage. It is a shame that the effort is for such a shit
         | purpose, but these "people" are not stupid, and not many other
         | areas offer these kind of challenges.
        
       | paxys wrote:
       | If you are even mildly technical you NEED to have a Pihole +
       | Tailscale setup on your home network and all devices. Block all
       | this malware at the root.
        
         | aembleton wrote:
         | Or change your DNS to use nextDns
        
       | aembleton wrote:
       | Sounds like blocking these tracking scripts using uBlockOrigin
       | probably prevents this. Another reason to use uBlockOrigin.
        
       | dmantis wrote:
       | Does that work across profiles? I have to use some apps from such
       | spyware oriented companies and usually put them in isolated
       | profile with shelter.
       | 
       | I wonder whether local ports opened in isolated "work" android
       | profile are accessible by main profile.
        
       | Aissen wrote:
       | Love the url slug: headline-to-come. It now redirects to a more
       | boring one though.
        
       | bnpxft wrote:
       | Another reason not to install big tech's apps and only use their
       | websites if you must.
       | 
       | Not only our their websites painful which discourages use,
       | websites are more sandboxed.
        
         | danieldk wrote:
         | I am not sure which Meta apps open ports, but e.g. Samsung
         | phones come with a bunch of Meta apps pre-shipped. IIRC just
         | removing the Facebook app is is not enough, there is another
         | service installed that is not visible as an app
         | (com.facebook.services etc.), which you can only uninstall from
         | the data partition with something like ADB/UAD.
         | 
         | Or buy an iPhone or a Pixel.
        
           | jmm5 wrote:
           | The Pixel "Private Space" feature should prevent Meta apps
           | from running in the background. It also prevents you from
           | getting notifications.
        
           | johnisgood wrote:
           | I tend to buy stock Android, e.g. Motorola moto g30, etc. It
           | still has lots of Google stuff, but you can get rid of them,
           | and I have a work profile specifically designed for Google-
           | related stuff, and my personal profile is de-Googled as much
           | as possible.
        
             | danieldk wrote:
             | I would recommend everyone who wants a clean Android to
             | look into Google Pixel phones. Aside from being mostly
             | bloat-free (and most bloat can be uninstalled), it is one
             | of the few phones that supports unlocking/relocking and a
             | secure open source alternative (GrapheneOS).
        
       | captn3m0 wrote:
       | Another similar tracking vector that lets any app detect all
       | installed apps by using android.intent.action.MAIN Query:
       | https://support.google.com/googleplay/android-developer/thre...
       | without the QUERY_ALL_PACKAGES permission.
       | 
       | No response from Google. Being used by dozens of apps in the
       | wild.
       | 
       | Edit: Original Research link:
       | https://peabee.substack.com/p/everyone-knows-what-apps-you-u...
       | (HN: https://news.ycombinator.com/item?id=43518866 , 482
       | comments)
        
         | maeil wrote:
         | Incredible that this was locked.
        
           | bossyTeacher wrote:
           | dang likely got told not to upset the benefactors
        
       | maeil wrote:
       | On many threads here regarding EU fines, I see the sentiment "The
       | EU only fines US tech to make a quick buck!".
       | 
       | It could be an idea to, you know, stop doing these things. Would
       | be great to see another few $billion fine for this one.
        
         | aucisson_masque wrote:
         | The us could fine US tech too.
         | 
         | I bet that most Americans would be ok with that, more privacy,
         | more money for the state and less to the greedy bastards.
         | 
         | EU doesn't have to be the cop of US technology, in fact it's a
         | bit pathetic to have another country policy your industry.
        
       | hofrogs wrote:
       | Doing something like this should result in Meta and such being
       | legally annihilated. But nothing will happen, as usual.
        
         | OsrsNeedsf2P wrote:
         | What's the crime?
        
           | hofrogs wrote:
           | Spying on users, connecting their real life identities to
           | their browsing history without their consent or knowledge?
        
           | kennywinker wrote:
           | Tracking users without their consent. This is a crime in the
           | EU. It's a crime that it's not a crime in the US.
        
           | autoexec wrote:
           | stalking? Maybe even something in the ECPA
        
           | lucianbr wrote:
           | Unauthorized access to a computer system. I'm sure if I
           | connected to some port on a computer belonging to Meta
           | without them wanting it, that would be the crime I would be
           | charged with. But somehow if Meta connects to a port on my
           | phone without me agreeing to it, it's not a crime?
        
             | nickphx wrote:
             | Yes.. and that listening service is their software that you
             | installed on your device... So caveat emptor.
        
               | genewitch wrote:
               | Software that came preloaded with what sounds
               | suspiciously like a rootkit to keep the background
               | service running on some phones.
               | 
               | Please don't "don't that phone then" because it's the
               | same all the way down to rotary telephones.
               | 
               | I still didn't consent to meta tracking me on my
               | telephone. I understand the shadow profiles and tracking
               | pixels and whatnot, but cmon.
               | 
               | Next year "actually meta was listening to conversations
               | captured by android devices and using it to target ads"
               | 
               | Don't use a cellphone? Meta and Google track desktop web
               | use. Don't use a computer? Okay, that's cool.
        
       | jurgenkesker wrote:
       | Ah yes, and every small Android dev is banned from Play and Admob
       | for tiny unknown reasons, with no recourse or way to communicate
       | with Google. But Meta here probably won't get any problems at
       | all. They should be temporarily banned!
        
       | qwertox wrote:
       | I wonder if companies like Wetter Online (from whom we know that
       | they're selling the location data to brokers [0]) or ad service
       | providers which offer libraries do the same.
       | 
       | If it were so, Google should be knowingly be allowing this to
       | happen and be a co-conspirator. I mean, they surveil our devices
       | as if it were their home. Impossible that they're not aware.
       | 
       | [0] https://netzpolitik-org.translate.goog/2025/databroker-
       | files...
        
       | josephcsible wrote:
       | Why don't all browsers, desktop and mobile, just block all cross-
       | origin access to localhost?
        
         | easterncalculus wrote:
         | For one I think it would break all those "update your BIOS via
         | your motherboard website" apps that probably shouldn't exist
         | anyways.
         | 
         | There probably are some legitimate uses, but I'm straining to
         | come up with them.
        
           | arunkant wrote:
           | Maybe just ask for confirmation
        
         | chedabob wrote:
         | I thought they did for resources and JS, which is why Meta have
         | to use WebRTC instead?
         | 
         | I think the Yandex one slips through because CORS does a naive
         | check against just what's in the header, not what it resolves
         | to?
        
       | chedabob wrote:
       | Does the Yandex HTTPS one mean they're shipping the private key
       | for their cert in the app, therefore anything running on
       | localhost (or on a network with poisoned DNS) can spoof the
       | yandexmetrica site?
       | 
       | There is a cert for it in the logs:
       | https://crt.sh/?q=yandexmetrica.com
        
       | worik wrote:
       | This is yet another reason for installing very few apps
        
         | ethbr1 wrote:
         | The reason to install very few mobile apps is directly
         | proportional to the effort companies exert to get you to do so.
         | 
         | And they push _REALLY_ hard.
        
       | neilv wrote:
       | Of course the ID was easy to abuse, and I assume Google knew
       | this, and also knew they'd need to have rules against abuse...
       | and that they'd need to back up the rules with penalties, like
       | Play Store permaban, legal action for damages, and maybe even
       | referral for criminal investigation (CFAA violation?).
       | 
       | Unfortunately, even if they did have such rules, in this case,
       | Meta is a too-big-to-deplatform tech company.
       | 
       | (Also, even if it wasn't Meta, sketchy behavior of tech might
       | have the secret endorsement of IC and/or LE. So, making the
       | sketchiness stop could be difficult, and also difficult to talk
       | about.)
        
         | ogurechny wrote:
         | Google and Apple are owning their whole operating systems. They
         | can do tracking directly in 50 different ways. Other
         | corporations routinely renegotiate deals on sharing the user
         | surveillance data with them, for big big money. So it all has
         | already been paid for, and authorised. The only problem is that
         | some stupid serfs are still making a fuss over it.
        
       | tomhow wrote:
       | We changed the URL from
       | https://arstechnica.com/security/2025/06/meta-and-yandex-are...
       | which is a report about this disclosure.
        
       | ugh123 wrote:
       | No doubt, whatever "vulnerability" is found, you have already to
       | agreed to it in some buried TOS.
        
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       (page generated 2025-06-03 23:01 UTC)