LinkedIn checks for 2953 browser extensions(github.com)
201 points bymdp2 hours ago |22 comments
cbsks2 hours ago
Looks like Firefox is immune.

This works by looking for web accessible resources that are provided by the extensions. For Chrome, these are are available in a webpage via the URL chrome-extension://[PACKAGE ID]/[PATH] https://developer.chrome.com/docs/extensions/reference/manif...

On Firefox, web accessible resources are available at "moz-extension://<extension-UUID>/myfile.png" <extension-UUID> is not your extension's ID. This ID is randomly generated for every browser instance. This prevents websites from fingerprinting a browser by examining the extensions it has installed. https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/Web...

rchaud1 hour ago
And they said that using a browser with sub-5% market share would cause us to miss out on the latest and greatest in web technology!
dana3211 hour ago
chrome was made by ex-firefox devs, chrome is still not as good!
awesome_dude1 hour ago
This is probably a naive question, but...

Doesn't the idea of swapping extension specific IDs to your browser specific extension IDs mean that instead of your browser being identifiable, you become identifiable?

I mean, it goes from "Oh they have X, Y , and Z installed" to "Oh, it's jim bob, only he has that unique set of IDs for extensions"

triceratops1 hour ago
It's not a naive question. This comment says it's not possible to do that: https://news.ycombinator.com/item?id=46905213
awesome_dude1 hour ago
Oh, it's (re)randomised upon each restart, whew, thanks for the heads up

edit: er, I think that that also suggests that I need to restart firefox more often...

tech234a40 minutes ago
The webpage would have to scan the entire UUID space to create this fingerprint, which seems unlikely.
throwaway80808118 minutes ago
Just have a database of UUIDs. Seems pretty trivial to generate and sort as it's only 16 bytes each.
b1121 hour ago
Maybe, but how long are the extension ids? And if they are random, how long to scan a trillion random alphanumeric ids, to find matches?

I presume the extension knows when it wants to access resources of its own. But random javascript, doesn't.

maples371 hour ago
The extension IDs are UUIDs/GUIDs, so 128 bits of entropy. No site is going to be able to successfully scan that full range.
b1121 hour ago
ChatGPT told me it can be done though.

It won't disclose how, as it says it has had several users report it. And that it expects 50% of the bounty, and will use it for GPU upgrades.

rdoherty2 hours ago
Skimming the list, looks like most extensions are for scraping or automating LinkedIn usage. Not surprising as there's money to be made with LinkedIn data. Scraping was a problem when I worked there, the abuse teams built some reasonably sophisticated detection & prevention, and it was a constant battle.
cxr1 hour ago
In order to create the data source that LinkedIn's extension-fingerprinting relies on to work, someone (at LinkedIn*?) almost certainly violated the Chrome Web Store TOS—by (perversely*) scraping it.

* if LinkedIn didn't get it from an existing data source

bryanrasmussen2 hours ago
from the code doesn't look like they do anything if they have a match, they just save all the results to a csv for fingerprinting?
cxr1 hour ago
"The code" here you're referring to (fetch_extension_names.js[1]) isn't and doesn't claim to be LinkedIn's fingerprinting code. It's a scraper that the researcher behind this repo wrote themselves in order to create the CSV of the data that they're publishing here.

LinkedIn's fingerprinting code, as the README explains, is found in fingerprint.js[2], which embeds a big JSON literal with the IDs of the extensions it probes for. (Sickeningly enough, this data starts about two-thirds of the way through the file* and isn't the culprit behind the bulk of its 2.15 MB size…)

* On line 34394; the one starting:

    const r = [{
                id: "aacbpggdjcblgnmgjgpkpddliddineni",
                file: "sidebar.html"
1. <https://github.com/mdp/linkedin-extension-fingerprinting/blo...>

2. <https://github.com/mdp/linkedin-extension-fingerprinting/blo...>

winddude1 hour ago
a problem for linkedin != "a problem". The real problem for people is the back room data brokering linkedin and others do.
hsbauauvhabzb2 hours ago
Wont someone think of poor little LinkedIn, a subsidiary of one of the largest data brokers in the world?
charcircuit2 hours ago
Why frame what you are trying to say like that? Businesses of all sizes deserve the ability to protect their businesses from abuse.
jmward011 hour ago
Do they respect my data? Why do they get to track me across sites when I clearly don't want them to but someone can't scrape their data when they don't want them to. Why should big companies get the pass but individuals not? They clearly consider internet traffic fair game and are invasive and abusive about it so it is not only fair to be invasive and abusive back, it is self defense at this point.
hsbauauvhabzb1 hour ago
They don’t need to track your web browser when they’re owned by Microsoft, because they track every action at a lower level.
missingdays1 hour ago
What lower level? Microsoft owns internet?
zelphirkalt1 hour ago
The operating system. For example see the Windows 11 screenshot debacle/scandal.
ronsor2 hours ago
I think they framed it this way because they don't consider scraping abuse (to be fair, neither do I, as long as it doesn't overload the site). Botting accounts for spam is clear abuse, however, so that's fair game.
hsbauauvhabzb1 hour ago
No, I consider all data collection and scraping egregious. From that perspective, LinkedIn is hypocritical when Microsoft discloses every filesystem search I do locally to bing.
dylan60446 minutes ago
Are you not scraping a site with your eyeballs when you view a site?
nitwit0051 hour ago
I'm sure there are issues with fake accounts for scraping, but the core issue is that LinkedIn considers the data valuable. LinkedIn wants to be able to sell the data, or access to it at least, and the scrapers undermine that.

They could stop all the scraping by providing a downloadable data bundle like Wikipedia.

compiler-guy1 hour ago
LLMs scrape Wikipedia all the time, or at least attempt to.

The data bundle doesn't help that at all.

sellmesoap2 hours ago
We enjoy the fruits of an LLM or two from time to time, derived from hoards of ill gotten data. Linkedin has the resourses to attempt to block scraping, but even at the resource scale of LI I doubt the effort is effective.
charcircuit2 hours ago
I am not denying that scraping is useful. If it wasn't people wouldn't do it. But if the site rules say you aren't allowed to scrape, then I don't think people should be hostile towards the people enforcing the rules.
ronsor2 hours ago
Well, they can try to enforce the rules; that's perfectly fair. At the same time, there are many methods of "trying" which I would not consider valid or acceptable ones. "Enforcing the rules" does not give a carte blanche right to snoop and do "whatever's necessary." Sony tried that with their CD rootkits and got multiple lawsuits.
b1121 hour ago
Yes, until it becomes abusive and malignly affects innocents.
schmidtleonard2 hours ago
The big social media businesses deserve a Teddy Roosevelt character swooping in and busting their trusts, forcing them to play ball with others even if it destroys their moats. Boo hoo! Good riddance. World's tiniest violin.

This is a popular position across the aisle. Here's hoping the next guy can't be bought, or at least asks for more than a $400M tacky gold ballroom!

xp842 hours ago
I mean, regardless of who they are or even if you don’t like what LinkedIn does themselves with the data people have given them, the random third parties with the extensions don’t additionally deserve to just grab all that data too, do they?
mathfailure2 hours ago
Surely they do! The data is in the public internets, aren't they?
ronsor2 hours ago
They'd put Widevine or PlayReady DRM on the website if they could, I'm sure.
bigfishrunning1 hour ago
why can't they?
josephg1 hour ago
Eh. I worked at a company which made an extension which scraped LinkedIn. We provided a service to recruiters, who would start a hiring process by putting candidates into our system.

The recruiters all had LinkedIn paid accounts, and could access all of this data on the web. We made a browser extension so they wouldn’t need to do any manual data entry. Recruiters loved the extension because it saved them time.

I think it was a legitimate use. We were making LinkedIn more useful to some of their actual customers (recruiters) by adding a somewhat cursed api integration via a chrome extension. Forcing recruiters to copy and paste did’t help anyone. Our extension only grabbed content on the page the recruiter had open. It was purely read only and scoped by the user.

hsbauauvhabzb1 hour ago
I say the same thing about my start menu sending every action I perform to bing.
minkeymaniac2 hours ago
I can confirm.. open up linkedIn.. hit F12 and watch the error count keep going up and up and up

Screenshots found here https://x.com/DenisGobo/status/2018334684879438150

bitbasher9 minutes ago
Looks like this has been known since 2019.

https://www.nymeria.io/blog/linkedins-war-on-email-finder-ex...

avastel1 hour ago
I wrote a blog post recently about the technique used by LinkedIn to do extension probing, as well as other ways to do it with less side effects

https://blog.castle.io/detecting-browser-extensions-for-bot-...

bastard_op1 hour ago
Chrome is the new IE6. Google set themselves up to be the next Microsoft and is "ad friendly" in all the creepy ways because that's what Google IS an ad company. All they've contributed to security is diminishing the capability of adblockers and letting malware to do bad things to you as consumers.
0xbadcafebee1 hour ago
He who controls the Ads, controls the Internet.
themafia1 hour ago
> Google set themselves up to be the next Microsoft

Google became a monopoly. All monopolies do this.

shouldnt_be1 hour ago
I wrote an article about it a couple of months ago. I also explain why, how and a way to prevent it.

https://javascript.plainenglish.io/the-extensions-you-use-ar...

jmholla1 hour ago
To clarify, you talk about why it's possible, not why LinkedIn is doing it, right? Or did I miss something in your article.
zahlman2 hours ago
> This repository documents every extension LinkedIn checks for and provides tools to identify them.

I get that the CSV lists the extensions, and the tools are provided in order to show work (mapping IDs to actual software). But how was it determined that LinkedIn checks for extensions with these IDs?

And is this relevant for non-Chrome users?

usefulposter2 hours ago
Technical writeup from a few weeks ago by a vendor that explains how LinkedIn does it, then boasts that their approach is "quieter, harder to notice, and easier to run at scale":

https://blog.castle.io/detecting-browser-extensions-for-bot-...

DrStartup1 hour ago
Setup a quick CDP connection. Have Claude Code attach and inject JS into Page.addScriptToEvaluateOnNewDocument. Loads before the page.

Typical early hooks: • fetch wrapper • XMLHttpRequest.prototype.open/send wrapper • WebSocket constructor wrapper • history.pushState/replaceState wrapper • EventTarget.addEventListener wrapper (optional, heavy) • MutationObserver for DOM diffs • Error + unhandledrejection capture

HumanOstrich50 minutes ago
This is irrelevant to the article and discussions here. Weird copypasta bullet points too.
shj21051 hour ago
what would this do?
mrkramer48 minutes ago
LinkedIn is the worst walled garden of all of them.
mongrelion2 hours ago
Curious question: why would they check for installed extensions on one's browser?
CobrastanJorji1 hour ago
Fingerprinting. There are a few reasons you'd do it:

1. Bot prevention. If the bots don't know that you're doing this, you might have a reliable bot detector for a while. The bots will quite possibly have no extensions at all, or even better specific exact combination they always use. Noticing bots means you can block them from scraping your site or spamming your users. If you wanna be very fancy, you could provide fake data or quietly ignore the stuff they create on the site.

2. Spamming/misuse evasion. Imagine an extension called "Send Messages to everybody with a given job role at this company." LinkedIn would prefer not to allow that, probably because they'd want to sell that feature.

3. User tracking.

xz18r27 minutes ago
I wrote some automation scripts that are not triggered via browser extensions (e.g., open all my sales colleagues’ profiles and like their 4 most recent unliked posts to boost their SSI[1], which is probably the most ‘innocent’ of my use-cases). It has random sleep intervals. I’ve done this for years and never faced a ban hammer.

Wonder if with things like Moltbot taking the scene, a form of “undetectable LinkedIn automation” will start to manifest. At some point they won’t be able to distinguish between a chronically online seller adding 100 people per day with personalized messages, or an AI doing it with the same mannerisms.

[1] https://business.linkedin.com/sales-solutions/social-selling...

jppope2 hours ago
most automations for sales and marketing use browser extensions... linkedIn wants you using their tools not 3rd party
Nextgrid2 hours ago
Their own tools suck, that’s the issue.
staticshock2 hours ago
For a social network, more information about their users = better ad targeting. It likely gets plumbed into models to inform user profiles.
Aurornis2 hours ago
Look at the actual list. It's primarily questionable AI tools, scrapers, lead generation tools, and other plugins in that vein.

I would guess this is for rate limiting and abuse detection.

HPsquared2 hours ago
An attempt at fingerprinting, I suppose?
dwedge55 minutes ago
I wonder if this is why the linkedin feed blocker I installed in Firefox 2 weeks ago stopped working for me within 24 hours
ta98853 minutes ago
So it really is espionage at all levels.
DOM10033 minutes ago
const nameA = getName(a).toLowerCase(); const nameB = getName(b).toLowerCase(); return nameA.localeCompare(nameB);

const msg = createDoneMessage(); msg.style.opacity = '1';

    console.log("Extensions sorted alphabetically!");
    console.table(sortedCards.map(c => ({
        name: getName(c),
        id: c.id || '—'
hasperdi1 hour ago
Another thing... they alter the localStorage & sessionStorage prototype, by wrapping the native ones with a wrapper that prevent keys that not in their whitelist from being set.

You can try this by opening devtools and setting

  localStorage.setItem('hi', 123)
input_sh1 hour ago

    cut -d',' -f2 chrome_extensions_with_names_all.csv | grep -c "AI"
    474
Only 16%!?
Aurornis2 hours ago
I suggest everyone take a look at the list of extensions and their names for some very important context: https://github.com/mdp/linkedin-extension-fingerprinting/blo...

I didn't find popular extensions like uBlock or other ad blockers.

The list is full of scammy looking data collection and AI tools, though. Some random names from scrolling through the list:

- LinkedGPT: ChatGPT for LinkedIn

- Apollo Scraper - Extract & Export Apollo B2B Leads

- AI Social Media Assistant

- LinkedIn Engagement Assistant

- LinkedIn Lead Magnet

- LinkedIn Extraction Tool - OutreachSheet

- Highperformr AI - Phone Number and Email Finder

- AI Agent For Jobs

These look like the kind of tools scummy recruiters and sales people use to identify targets for mass spamming. I see several AI auto-application tools in there too.

NicuCalcea50 minutes ago
LinkedIn itself provides tools for scummy recruiters to mass spam, so this is just them protecting their business.

Also, not all of them are data collection tools. There are ad blockers listed (Hide LinkedIn Ads, SBlock - Super Ad Blocker) and just general extensions (Ground News - Bias Checker, Jigit Studio - Screen Recorder, RealEyes.ai — Detect Deepfakes Across Online Platforms, Airtable Clipper).

tech234a1 hour ago
See also: a demo page for the same technique that can enumerate many extensions installed in your browser: https://browserleaks.com/chrome
xnx54 minutes ago
Yuck. Disgusting that extension detection is possible.
unstatusthequo1 hour ago
I’m probably on the list. I made a LinkedIn Redactor that allowed you to add keywords and remove posts from your thread that included such words. It’s the X feature but for LinkedIn. Anyway, got a cease and desist from those lame fucks at LI. So I removed from the chrome store but it’s still available on GitHub.