Tell HN: Cloudflare silently injects its analytics when you switch nameservers
A few hours ago I switched my nameservers to Cloudflare in order to enable R2 bucket serving through my own subdomain, and I found out that it silently had injected a JS analytics snippet in my HTML-only JS-free site textlog.cc — I had to go to the Analytics dashboard, Add the site to the analytics and then disable the snippet. I find this approach entirely invasive, you should opt-in to features like that not have to opt-out. Just a warning out there to folks who might not be aware of this.
You are using MITM proxy as a service. In addition to analyzing all traffic and blocking legitimate users with captchas, they can inject stuff in there, too.
An alternative: <meta http-equiv="Content-Security-Policy" content="script-src 'self' https://only-scripts-allowed-from-here.com">
This makes the client only load self-hosted scripts, or scripts only from the specified origins, among the other directives CSP allows (e.g. restricting styles, images, frames, etc.): https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/CSP
If Cloudflare (CF) has r/w access to the response body, which CF does have by default, then CF can easily modify or remove that <meta> tag. The risk is not abated
The risk of third parties injecting scripts, etc., e.g., analytics, advertising, etc., into response bodies (web pages) is usually cited as a rationale for using HTTPS^1
CF somehow avoids the usual objections. CF is a MiTM but few people object
1. For example, a data collection, surveillance and advertising services company that operates a www search engine and releases a web browser may not want an ISP to inject scripts, etc., e.g., analytics, ads, etc., into web pages as it might compete with the company's business. As a defense against such ISPs and other third parties that are potential competitors for data collection/surveillance/advertising services, it might favor HTTPS sites in its www search engine results, promote HTTPS at conferences discussing its web browser, etc.
Thanks for the background context, very interesting and realistic. Yes, of course it also has read/write access, though I always make sure there’s no interference of that kind. It has only happened to me once, where a binary I hosted on Pages didn't work when downloaded with wget (though that happened several years ago).
FWIW, I operate own DNS (including own custom root.zone) and I MiTM own TLS traffic with a localhost forward proxy. With this setup I get r/w access to response bodies, I add a CSP as an HTTP response header, and a long list of other traffic manipulation. There is no tracking, ads, telemetry, etc. Nothing leaves the computer unless I allow it. Operating DNS plus forward proxy gives me lots of control
Letting Cloudflare (CF) operate DNS and direct traffic through its proxies gives CF control
It's interesting to see how they use it under market pressures
This is a tangent, but your setup sounds interesting to me — would you share more about how to configure such for myself?
Many years ago I started to describe how it works in an HN comment and some reply complained about the idea of terminating TLS, i.e., decrypting, and then re-encrypting. Obviously this sacrifices something, e.g, speed, in order to gain _control_
But this is what Cloudflare does and no one seems to mind
Large companies also do this to protect their LANs
I'm not running a CDN, only a small home LAN. I'm only procesing a small amount of traffic on a personal computer. This setup is fast enough for me, it's not slow at all
The basic configuration is generally:
1. Configure DNS to point to the local proxy listening address #1, a local address, e.g., using a wildcard in a zone file
2. Configure the proxy to terminate TLS, "do stuff", and then forward to proxy UNIX socket path #2 or proxy listening address #2
3. After doing the stuff, the proxy then sends the traffic over the internet
The "do stuff" part is personal. It depends on what one wants to do. There are seemingly endless possibilities
It's not likely the constantly changing configurations I use would be suitable for others. It's all based on personal preferences and usage habits
I rarely use a graphical browser, for example
I don't make piecemeal remote DNS queries like most www users. (IME, most A RR's stay the same over long periods.) I get bulk DNS data periodicallly from a variety of sources and load it into the proxy's memory. When I make an HTTP request there is either no DNS lookup because I'm using the IP address of the proxy or there is a single, local DNS lookup which returns the address of the proxy. There is no access to remote DNS
When I first decided to start inspecting own TLS traffic by terminating and re-encrypting, I initially tested the idea using socat
After I saw that it worked, I started using other software like haproxy
I never expected this approach would work well enough but many years have gone by and I'm still using it. The configurations I use are much longer and more complicated than any sample I have ever seen on the www
It's funny that Cloudflare is decrypting and re-encryting _other peoples'_ traffic, and this is thought to be AOK, but aside from large companies few people seem interested in doing this with their _own_ traffic on their _own_ computers on their _own_ networks
It can be useful, IMHO
Also can add "Cache-Control: no-transform" header, which prevents modifying the payload.
Does it prevent it? Or just request it? There's no way to enforce that is there?
CF owns it all, coming and going (request handling and response writing), thus can choose how/whether to interpret, ignore, modify or append any headers.
script-src 'none' is a more secure solution.
You are right that Cloudflare enabled these analytics by default for our free plans in Septemeber of last year.
We built Real User Measurement (RUM) into our free plans because it gives site owners actionable performance data they would not otherwise have. It is on by default for free sites fr the reasons we wrote about in the blog post below. It is easy to disable if you don't want it on. All of our paid plans are opt-in only.
This also gives free plans access to our Observatory product at no cost. Observatory is a performance-monitoring tool inside the Cloudflare dashboard that combines real user data with simulated lab tests to help you measure and improve your website speed.
Blog post: https://blog.cloudflare.com/the-rum-diaries-enabling-web-ana...
> measure and improve your website speed
inserts 31KB JavaScript into tiny HTML pages.
If RUM is such a good thing, why is it opt-in for paid users? Why push this gracious gift only onto free users?
I have broadly good feelings about Cloudflare but this warrants a response.
Because if something is free, you are the product.
Because paying business customers are a lot more sensitive to this type of change rolling out. They are particular about how they want their shit hosted. Which is totally fair. People on the free tier probably a lot more interested in free benefits and care less about a little change in their hosting.
Cloudflare needs the data. Useful to validate the impact of changes, build marketing content... Using the free tier for this is fair, they let you opt out, they give you a dashboard.
If someone is mad, maybe they should pay or use a different architecture.
Shill
I'm not a Cloudflare customer and don't intend to actually use their services. To be transparent I got a free account for few experiments. I'm not working for them at all.
When it's free you know you are being used, collecting data is the game.
> this is fair, they let you opt out, they give you a dashboard
So they give you something else you didn't ask for and therefor it's "fair"? I think it's pretty dubious to extend services with such data collecting features without informing affected users first, and making it clear how to opt-out before its deployment. A blog post won't do, no.
Wow, this is ridiculous. Sites that have been running on Cloudflare for a decade+ silently got the treatment. Why the hell was there never a big banner telling me about this? I frequently log into the console.
I get it that by being on the free plan (well I do pay for Registrar), I'm the product, but I also converted employers to paying customers of yours based on goodwill. This just destroyed about all of that, among other things. If I haven't given a damn about "powerful, in-depth monitoring solution that helps you debug and optimize applications" in over a decade, I certainly won't suddenly be "excited" about it when you sneakily inject it.
> It is on by default for free sites fr the reasons we wrote about in the blog post below.
Nowhere in the blog post does it give the reasons why it's A. on by default for free sites B. off by default for paid sites.
What an amazing display of double speak. The only thing I didn't get is how is the DOW doing?
Btw I remember another time you tried to manipulate the DOM of peoples websites. It lead to Cloudbleed.
Not sure what is more appalling. Silently injecting javascript tracking, or writing a marketing-speech response like this without any substance at all
Is this even GDPR-compliant?
> "gives site owners actionable performance data they would not otherwise have"
As I understand, the next step will be to inject ads, to give CloudFlare actionable monetization strategies they would not otherwise have.
Indeed, https://blog.cloudflare.com/the-rum-diaries-enabling-web-ana...
Perhaps it drowned in newslop when announced?
The RUM Diaries: Enabling Web Analytics by Default
(2 points, 11 months ago): https://news.ycombinator.com/item?id=45291323
(1 point, 11 months ago): https://news.ycombinator.com/item?id=45339321
I noticed that there's very little non-AI stuff of value that gets to the front page nowadays
If you're only using Cloudfare for DNS, but HTTPS connections go directly to your server, how does it inject HTML?
You must be allowing Cloudfare to terminate your HTTPS connections; i.e. using them for actual proxying.
The orange cloud icon in dns settings, in other words, but that's opt-out too. So yeah - double opt-out I guess.
I have no idea what 'the orange cloud icon' means, as I'm not a CloudFlare used.
But DNS/Name servers do not see HTML traffic, as the above poster mentioned, so it's not obvious how this change would matter.
Is it that they are serving their HTML via CloudFlare, and cloudflare is making changing in its serving of their html?
Cloudflare sets up a reverse proxy as part of their core offering, so by default they can MITM your proxy. The “orange cloud” by a DNS record means it points to their proxy instead of your server.
What a shame. I wasn’t expecting these dark patterns from Cloudflare at all.
That's how you get DDOS protection / edge delivery, so it's not a dark pattern. I imagine it's the main reason why people would DNS through them in the first place.
An “orange cloud” with no other indication to represent a feature that is enabled-by-default (with implicitly enabled analytics) sounds like quite the dark pattern. The UI makes the DNS record seem to point to A (your entry) but actually points to B (Cloudflare). This isn’t an oversight, it’s an attempt to obfuscate.
Even if the choice to enable it by default makes sense for Cloudflare’s userbase, the implications are hidden and non-obvious.
The options are actually labelled as 'Proxied' or 'DNS Only', so that is actually quite clear.
It's essentially the entire reason to use Cloudflare.
As sibling mentions it is indeed labeled and not just some icon. People just refer to the orange cloud UI for it for convenience and because it makes it easy to spot whether you have it on or not.
But regarding the icon, the icon is their company logo, it really is the primary feature. It's also not like you have to go find it in settings to turn it off after adding DNS record, it's part of the form when you add the record (default on, yes), and it's prominent when viewing the record.
I would say that Cloudfare having customers who don't know exactly what they are getting (into) is actually a Cloudfare problem they should take responsibility for.
That’s not a dark pattern. That’s one of the core reasons to use Cloudflare.
The OP doesn't understand what they are configuring they have Cloudflare setup as a proxy.
This reminds me of the old free hosts that would inject their own scripts/ads on pages hosted by them, but their implementation would do it only after detecting the closing HTML tag (either </body> or </html>, can't remember) and the various tricks to get around it, including omitting the tag (browsers don't care), rAnDoM case tags (some were hardcoding lower or upper and comparing case-sensitively), and messing with the content type and relying on the browser to detect correctly since it didn't inject into other types (not sure how the current browsers will handle that).
I'm getting flashbacks to Proxomitron, a localhost proxy in the HTTP days when it was also much harder/impossible to make browser plugins.
Are you using CF as a proxy or only for DNS? I ask because I just went to check my domains on the dashboard (some purchased a few years ago, one purchased just a couple days ago), and none of them have Web Analytics enabled.
I have all my domains set to DNS only, so no CF proxy. Wondering if that is why?
I just went and switched them to DNS only, they were on Proxy by default, that also should have been opt-in. Maybe I missed the option while switching the nameservers because I did it in a hurry but still.
> that also should have been opt-in.
The proxy is like 99% of why people use Cloudflare
A simple screen when I did the switch that requires explicitly ‘Enable Proxy’ or ‘skip for now’ would have been enough. Also for ‘Enable Analytics’. None of these existed, or not very obvious otherwise I’d seen them.
In the DNS screen there is literally a column "proxy status" with the only color besides black and white being the orange of proxy enabled
I agree it is a bit confusing, but it makes sense if you think about the expected default use case, which is enabling the cloudflare CDN for customers. They expect people to be using their CDN.
I use them for my registrar, because they offer domains at cost and you can’t beat that. But yes, they make it an extra step to use them without using the CDN.
Once you figure it out, it is fairly straightforward, though, and you can’t beat the price.
If a registrar requires you to use their own nameservers, then they are no longer comparable to other registries.
With the supply chain attacks happening in the JS ecosystem, this reminds me to advise against using CDN's.
Is there an entry in filter-lists used by ublock and other client-side content blockers for `https://static.cloudflareinsights.com/beacon.min.js/`?
Yikes! I see this too:
<script type="module" src="https://static.cloudflareinsights.com/beacon.min.js/v4513226..." integrity="sha512-ZE9pZaUXND66v380QUtch/5sE9tPFh2zg45pR2PB0CVkCtOREv2AJKkSidISWkysEuQ0EH8faUU5du78bx87UQ==" data-cf-beacon='{"version":"2024.11.0","token":"c0859b51a7804ab5a9cc8e9e2b2c4cde","r":1}' crossorigin="anonymous"></script>
Yup, I explicitly had all anaytics turned off. But had a few sites using Cloudflare for caching. Now I'm checking and seeing this on all of them. This is gross and unacceptable. "Caching" does not mean "modifying my site".
MITM attack, that's what it is. Why is this not in the news? Ah, no one cares.
Why is this not in the news?
Good point. There should be a place where hackers can get this kind of news. Some kind of Hacker News place.
It takes a lot of trust to let a CDN be able to terminate TLS traffic for you and this doesn't exactly give the warm fuzzies.
Adding a RUM beacon for observability / performance metrics capture, as an opt-out feature for free plans (opt-in for paid plans), is not exactly nefarious. Hopefully/presumably there was some communication before the change was rolled out.
No. I was on a free plan for years and found out by accident. It's interesting that you set "nefarious" as the bar. I'd simply call it "sleazy".
I'm not seeing this on my site (if you want to check: https://stackgho.st), are you using their `strict` http settings? I.e. is your server terminating TLS or is theirs?
edit: perhaps it's only for sites added after that policy came into effect
Isn't this well known when using CF as a proxy? Not sure how they would provide traffic / DDoS telemetry otherwise.
They're serving the HTML, they have every ability to track individual web requests without modifying the content they're serving.
100% But this does not give you any useful personal data :)
Or data for the increasingly invasive Cloudflare captcha.
Yes, they add the js if "web analytics" is enabled. I believe I had to manually enable it on my old sites though. Maybe it's enabled by default when adding new domains?
No, I hadn’t enabled for any site. I had to enable first to turn it off.
Maybe send it to them as a bug. Seems more like a mistake than malevolence.
They have a blog post about it so they know what they're doing.
> injected a JS analytics snippet in my HTML-only JS-free site textlog.cc
Cloudflare injected hostile code into a site they are not even hosting? If it's HTTPS, how do they even do that?
Does it violate the "exceeds authorized access" provision in the Computer Fraud and Abuse Act?
The most likely answer is the person accidentally enabled the cloudflare reverse proxy without understanding what they were doing.
It seems incredibly unlikely cloudflare does this when just DNS hosting, if for no other reason then that this would break so many things.
I can’t recall if there was a setting to enable reverse proxy, if there was it was On by default since I didn’t expect to have reverse proxy enabled as well. But you can also rp without injecting a script. That’s overdoing it.
If the cloud symbol is orange, it's enabled. I believe they'll even warn you if you disable it, a lot of people enable it unintentionally.
I don't know what happened in this situation but beware that CF and similar providers are not true DNS hosting providers. They do DNS, but only so their CDN stuff works, and to lock their customers from using whatever DNS hosting they want. Various things that one might reasonably want to do with your DNS zone are not possible with their product. So use it only because you need to do so in conjunction with their core services.
If this is HTTPS, how would Cloudfare have the certificate for your domain so that browsers don't warn about a mismatch?
Or is it that when you sign over DNS to a provider, they can take over your cert? They can "ass-cert" their own? :)
As far as I know they terminate all TLS; it’s one of the tradeoffs using them.
They have a product called Magic Transit that offers DDoS protection and such for plain IP traffic, where Cloudflare does not terminate TLS. Pricing is not public but starts in the five-digit USD per month range according to people I talk to.
This may tell you something about how keen Cloudflare are to handle traffic they themselves cannot decrypt.
Magic Transit uses BGP magic to work. That only makes sense at scale - i believe you have to have your own ASN for it to work.
Realistically its a totally different product, and 5 digit price is probably cheap relative to competitors in that space.
Yes, the person who controls the DNS controls the certificate.
What a certificate is supposed to verify is that traffic is going to the right place. If you designate cloudflare as the rightful host of your website then they can get a certificate.
This isn't an edge case though. This is cloudflare's primary product. It is why users use them.
When you set up CNAME and certain other records in Cloudflare DNS, it defaults to (and heavily discourages you to disable) "proxied" records, which I believe means that the record points to a Cloudflare-owned host which then acts as a reverse proxy to whatever value you'd set. So from the console it looks like you've set the CNAME to a certain value, but in practice it'll be set to a different thing and transparently forward everything via Cloudflare. This is probably where the analytics get inserted, alongside a bunch of other Cloudflare features.
You can disable this, at which point the record will be set as a normal DNS record.
I can see the advantage of Cloudflare's proxy systems, but I wish they'd be clearer about when they're being used and not pretend that this is some DNS feature or that records have been set to one thing when they've actually been set to something else. If nothing else, it makes debugging DNS issues a lot more confusing, particularly if you're not a DNS expert.
>I can see the advantage of Cloudflare's proxy systems, but I wish they'd be clearer about when they're being used and not pretend that this is some DNS feature or that records have been set to one thing when they've actually been set to something else. If nothing else, it makes debugging DNS issues a lot more confusing, particularly if you're not a DNS expert.
You could say the same about the reverse, ie. people set up their site on cloudflare, thought it was "protected", but really it's dns only and their servers are wide open. It's even worse if they migrated from another provider that was providing ddos protection.
On the other hand. Proxying websites (for ddos protection, cdn, etc) is their primary product. Its what they are known for.
I think a better question is: why would you be using cloudflare, if you didn't want that?
There's still a naive expectation that the proxy isn't going to inject invisible content on your site that hits when you realize you were being naive.
> It seems incredibly unlikely cloudflare does this when just DNS hosting
Not to mention impossible when ‘just’ DNS hosting. Though I suppose they could secretly replace the stated IP with one of their own anyway and then still proxy the content.
TLS terminates at Cloudflare, not at your origin. When a record is proxied (the orange cloud), CF holds the certificate the browser validates against and opens a separate connection to your server, so it sees plaintext on both sides and can rewrite the HTML on the way out. Same mechanism that makes the WAF and caching work, so it isn't specific to the analytics feature.
Worth checking which of your records are actually proxied. DNS-only ones (grey cloud) pass straight through and can't be touched.
Here we go. First, get everyone on the internet to use a free service (nameservers and CDN caching, which BTW is mostly unnecessary for pretty much everyone out there). Then, inject analytics, to "give site owners actionable performance data they would not otherwise have". Then, inject ads.
In the meantime, also implement "bot protection" and get everyone on the internet to outsource the decision on who can access their website. With no appeal.
I'm increasingly worried about Cloudflare.
Thank you so much for info about this. Does anyone has list of known "traps" like that on Cloudflare? I only want to use them for proxying my IPv6 website, SSL, and nothing else.
There are countless objections to many of the things the Cloudflare is doing. If you only need it for a small number of things perhaps it may be worthwhile to look if at whether there are alternatives to CF for those use cases.
Took me a minute to realise this isn't 1.1.1.1 (which Cloudflare also runs), but their original website DNS hosting service.
I noticed the same thing with email-decode.min.js on my site. It turns out it's the "Email Address Obfuscation" feature, which I didn't expect to be on by default.
Thank you for this. I indeed had it up on mine. Cloudflare has switched defaults a couple times now, which honestly is wild to me.
yep, last website I did was JS free 100% except that pesky cloudflare script
Is there an opt-out mechanism at least? CF is burning goodwill in months it built over the last decade.
Yes there is. I have it disabled on mine:
https://limereader.com/
If you navigate to the domain itself, then to Analytics > Web Analytics there's a Quick Action for the RUM Settings.
It's not necessary to use Cloudflare hosted DNS to use R2 with a custom subdomain.
Make a CNAME record the same way you would for a CDN subdomain.
(I am not yet running this in production, YMMV.)
Then you don't get edge cache though, right? And maybe some other features?
Noticed this the other day as well. Sketchy as fuck. I didn't have analytics enabled. I had to go and enable to get access to the option to turn this off
Spies. Spies everywhere
You left out the part about how you use them as a reverse proxy, which is decoupled from DNS. One is coincidental; the other required.
If they can inject script, they can also snoop on all your cleartext traffic without you knowing....
Indeed. I have several domains using cf for dns only and they don't/can't inject anything into those sites.
"can't" is incorrect. As your name server, they can decide to turn the reverse proxy/caching at any point in the future, write an obscure blog post about how this is the best solution for all (a post that gets 2 comments on HN due to other news that week), and you'd only find out about it 11 months later in a thread like this one.
Oh gosh I didn’t enable anything like that also. I just wanted the nameservers in order to serve the bucket under my subdomain. What else is there I wonder?
Ok to turn this off you go Domains → Overview → your.site → DNS → Records → then Edit each entry to DNS Only (gray cloud). MITM gone now (I hope).
OK, how can Cloudfare edit your HTML without it passing through your server?
If the browser connects directly to your web server, how can there be Cloudfare's analytics stuff?
Check what IP address you are connecting to when you load textlog.cc. Is that an address that you control? If it's not an address that you control, where is it getting your page, and is that not called proxying?
The main reason anyone chooses cloudflare is for their CDN (which I suppose is a "reverse proxy"...not a way I'd refer to it but technically yes that's essentially what it's doing). If you don't need the CDN or any of the other fancy features there are plenty of straight DNS providers out there (and often provided by the registar these days).
Why would they snoop your traffic?
Ah, because they can.
What else would you expect from Cloudflare?
It this point in time it is somewhere between GoDaddy and RyanAir in dark pattern usage
Why do people care? This is hardly anything malicious.
Hardly anything malicious ... yet and even that's debatable.
Yes, when you proxy anything through Cloudflare (CF) you give up on having your contents encrypted as CF terminates the TLS endpoints, but going from this to changing the content of the served site and injecting JavaScript is quite a big step and likely not what a lot of people would want nor expect. Your JavaScript-free site becomes a site that ships JavaScript without you knowing or having done anything.
Additionally, this introduces additional tracking of users, which a lot of people don't want.
And finally, there's the slippery slope. Today it's RUM, tomorrow it's ads or something else? Once CF starts modifying the user's content, what's stopping them from doing it more and more?
Maybe don't use CF if you don't want someone fucking with what you're serving. It's their entire raison detre.
We use Cloudflare tunnels for connecting distributed workers to central infrastructure. Haven't seen this on tunnel traffic, but good to know it happens on nameserver-managed sites. Another reason to audit what your CDN injects — same applies to checking your security headers regularly.
To add to your experience: It was also very hard, for me, to find the setting that disables this JavaScript.
A public service reminder to anyone setting up their domains that there are many alternatives to Cloudflare, like EG Bunny.net (I am not affiliated, just a happy customer) and that by using one of these other DNS providers, you
- play your small part in keeping the Internet open
- delay or avoid entirely the enshittification that is 100% foreseeable when buying the "free" services of a quasi-monopoly vendor.
If you're not an enterprise customer, alternate providers will also give you every single feature you could ever need and more, and fewer surprises like the OP's.
if you aren't paying, you aren't buying
Surprise! The man in the middle man-in-the-middles! This is only the beginning, when you’ll get used to this they’ll do worse and worse, enshittification, remember?
If I wouldn't know it better I'd sometimes think some of the big tech shops are just fronts for centralizing the net.
Cloudflare is doing this already. Once they had enough monopoly power, they started a program to block all bots that don't undergo invasive KYC procedures. Eventually, they might become a KYC broker for regular browser users too. The free internet is over.
#savetheinternet
I don't know what would give anyone that idea. [1]
[1] - https://www.youtube.com/watch?v=a3Xxi0b9trY
That's exactly what they are.
And they can fuck off.
cloudflare is malware, what did you expect?
No it's not. You don't have to like them, but malware is "any program or file built to damage, disrupt, or secretly gain access to a computer, phone, or network". Cloudflare is many things, some good, some bad, but they don't secretly gain access to your system, you have to choose to install it, so it's not malware.
You choose to install it on your website if you own a website, but if you're surfing the world wide web, then a lot of the places you visit are increasingly being gatekept/hidden behind Cloudflare pages meant to "challenge" you if you take anti-fingerprinting measures.
Presumably these include any measures which would counter their operating model of tracking users on the web, under the excuse of stopping bots.