Is this real? This seems so ridiculous it makes me wonder for how long this CA has been in circulation in systems and if it has been exploited by someone previously discovering it in that time (state level actor or not). My old phone running Android 6 does not have any certificate from EMudhra, at the very least.
There are plenty of ways you would never be able to tell if a fake cert had been generated and used via this attack vector (let's ignore validation attacks):
1. CT does not do anything if a state actor demands a CA in its borders generate a cert without publishing to the CT logs (or a three-letter-agency doing this illicitly). They can put SCTs in the cert, and still not publish to the logs, nobody is auditing the logs for every cert every browser sees.
2. Browsers won't check for SCTs in certs if they come from a private CA. you can MITM any domain through ZScaler all day long and nobody will notice
3. Wildcard certs make it easy to make/renew a cert that looks normal but hides requests on new/different hosts
I feel somewhat confident in speculating that a bunch of people at large companies will, in fact, be auditing the logs following this. That’s their main value; they’re not really an online/active prophylactic.
Nope. You can find this from the Chrome Root Program.
> Because no TLS certificates chaining to these six intermediate CAs were logged to CT prior to our CRLSet block on October 17, no fraudulent certificates issued by these CAs could have been trusted by default in Chrome or other CT-enforcing browsers.
To be clear, emSign is another name for EMudhra, and Comodo is now known as Sectigo. (You can't just look at the organization name in a certificate subject; you have to consult the CCADB: https://www.agwa.name/blog/post/the_certificate_issuer_field...)
Definitely not. Their CPS requires that these keys be generated by an HSM and no HSM would ever generate these, so there's little reason to believe they're following any of their other controls.
I am shocked that one of the private keys was literally “4”. Anyone could have broken into this. I really hope there is an industry-wide effort to stop things like this in the future.... but I doubt it.
There is a variety of projects and researchers scanning for weak keys; possibly that's how this was found (haven't seen anything on that). These certs existed for a year and a half; that's bad but could be worse still.
One of the issues with sub-CAs (well, X509 certs in general) is that they can be ghosts in that there's no way you'll ever get it as a response on a TLS connection, so automated scanners on that won't find it.
CT should cover this (i.e. expose the cert so you can check for weak keys), but I have no idea if/how CT works for sub-CAs. [ed.: see below, doesn't seem to be in CT]
> One of the issues with sub-CAs (well, X509 certs in general) is that they
> can be ghosts in that there's no way you'll ever get it as a response
> on a TLS connection, so automated scanners on that won't find it.
Could you expand on this? I don't have a full grasp of what you're saying (I'm not super knowledgeable in CA stuff).
My understanding is that if something, like a browser, connects to a SSL site, they will either have or can obtain, one way or another, a complete chain all the way up to the root, so there can be no "ghost" certificate. And I would imagine a scanner could do all those same steps, and thus access all the same certs.
Is this a deficiency in scanner software? You seem to indicate it is a fundamental weakness in X509; I'm just trying to understand what.
Could you maybe describe a specific example of what you're describing?
In the most extreme case, you can just issue a certificate and not use it anywhere. If it leaks, it's still a security issue, because it's valid.
More realistically, especially with sub-CAs, they might only be used on e.g. corporate networks. TLS scanners may not be able to reach any of the hosts that uses such a cert. As the sibling post points out, clients checking for the cert in Certificate Transparency logs counters that (adding a requirement that the cert be publicly known, which TLS/X509 by itself very much does not have) — but of course this only helps if your client does CT…
Ah okay, thanks. So to be concrete, something like automation running 'curl' on an internal network might see the full chain, including the weak cert, and be vulnerable, but scanners on the wider internet won't see it. I was confused by "...there's no way you'll ever get it as a response on a TLS connection..." — I guess you just meant a _public_ TLS connection. Or it could be otherwise installed on corporate machines' local cert bundles.
If you're doing a MITM attack, you can selectively intercept certain clients, and only serve the compromised certificate in those cases only. Automated scanners won't pick that up. None of this actually works though, because browsers started mandating certificate transparency.
For their own stuff, Mozilla has talked in the past about specifically just only trusting intermediates they've seen. Their modern root agreement says the CA will disclose all relevant intermediates, so arguably they have a complete list and further if that CA "forgot" about a few of them whether that's because your firm is too disorganised ("Oh, right, the one on Barry's laptop, forgot that one") or an actual attempt to sidestep this rule - then we certainly don't want to trust these undisclosed intermediates, do we ? They're either purposefully shady, or they're forgotten about and likely never have been audited.
Nothing for "CN=EM DV TLS CA - G3B,O=eMudhra BV" (not sure which sha256 this uses, 2nd is the spki sha256)
I should be clear here my understanding is/was these are sub-CAs. Apparently they're (trying to be?) roots themselves? The point of logging a root cert in CT is somewhat moot… though tbh I would argue anything issued by a CA should be in CT logs, even cross-signing another CA that is becoming a root itself.
The impact of this incident is very unevenly spread.
Over 10 years ago, Mozilla shipped OneCRL [1]. We remediated this incident in a couple of hours for Firefox users who were protected automatically without the need for updates. Chrome, Apple and Microsoft have similar tooling. Since then, we've built more advanced tooling to handle revocation at scale for leaf certs (CRLite [2]).
However, for the rest of the ecosystem, there has been little to no investment in revocation and for those clients, this is a massive problem. Hopefully, we'll see folks invest now. Efforts like upki [3] look promising.
Firefox Mobile 158.0 on Android 17 (Pixel 7) connects to all the demo sites with zero warnings. Any idea why the "automatic protection without updates" doesn't seem to be working with that combination?
Pixel 10 with 158.0.1 still connects to the emSign ones, even though the patch notes for 158.0.1 mention that it updates the CRL for those without 'Remote Improvements' enabled?
edit: Disabling all the eMudhra CAs in Android settings does nothing, cool?
edit: I guess there's no way to manually ask for CRL update, cool??
edit: Gave up and reinstalled Firefox. Seems to be fine now.
I'm hoping some organizations will step forward to fund work on this.
(Note that curl on Ubuntu 26.10 now has CRLite support baked via upki -- unfortunately that doesn't help with this because AIUI CRLite is only for end entities, not for intermediate certificates.)
It's very inconsistent for me even on just Firefox. On multiple systems running different instances of Firefox, checking with https://emudhra.we-have-a-problem.com/:
One blocks everything; one blocks 6 out of 12; one blocks the other 6 out of 12; one blocks nothing.
You mean you and Chrome stopped supporting normal CRLs and OCSP, replacing (for normal users) these distributed-trust technologies with central lists controlled by browsers
You mean the response was uneven. The impact was a complete and total potential compromise of literally everyone. Every domain. Every client using one of the public root programs. Every user of those clients.
I mean, it's an emergency, but the acute severity is debatable; many times a month the major browsers quietly deal with vulnerabilities that yield attackers direct control of victim computers; here, attackers get the ability to spoof websites if they're in a position to hijack connections.
The middlebox situation, with non-updatable roots, is very annoying. But middleboxes also have unfixable RCEs, so...
It's totally fair to evaluate different projects by how well positioned they are to update their WebPKI trust anchors. I'm just saying, keep perspective.
So it other words, it allowed attackers to do the one thing that Web PKI is supposed to prevent.
Being able to quickly update trust roots is at best a hack to paper over the issue when there is no good reason why every podunk CA should have authority to generate certificates for every domain in the first place. It's an inexcusable design flaw. Or a feature that gives power to root stores at the expense of everyones security, from the perspective of the root store operators.
Keep in mind that a _lot_ of software out there uses TLS as its only trust anchor for updates, commands or similar.
This can and will be weaponized for take-overs of systems. They will be of the consumer kind, but they will also be of the industry kind. Let's pray that they will not be of the state or military kind.
The screening process has been more involved in that since around the late 2000's. I wouldn't call 20 years "very recently," especially in the context of the history of the web.
Which is to say, sub-CAs in itself are a giant loophole that needs plugging. Especially since AFAIK nobody is bothering with name constraints (RFC5280 section 4.2.1.10).
eMudhra is also a root CA operator. One root CA operator cross-signing another root CA operator is a good thing actually, and it's what allowed Let's Encrypt to work before their root certificate was widely trusted.
Issuing sub CAs to non-root operators has historically been a big loophole though it's not as bad these days since multiple root programs now require approval before CAs can do it.
Didn't Let's Encrypt have to jump through all sorts of hoops to prove they were competent and trustworthy before that happened?
Now it's coming out these guys used "4" as a private key. That's a crazy amount of incompetence and malfeasance. Did they vibe-code a CA? HOW DOES THIS HAPPEN? I am dumbfounded.
You couldn't even do this if you installed Microsoft Small Business Server 2008 today, unpatched, with the CA on default settings.
They hold intermediate certificates issued by TWO different root CAs, neither of which they operate.
So two separate entities didn't bother to read their certificate policy or inspect their operations. Have we not learned anything from past mistakes?
Roots should be responsible for all their sub-CAs, full stop. If they don't trust them enough to accept that responsibility, then the system is broken.
The reason nobody bothers with NCs is because they don't work very well in practice. They also have their own baroque matching rules that are not intuitive if you're from the land of UNIX globs.
(In fairness this is a self-fulfilling prophecy: a lot of validators handle NCs poorly or not at all, so there's no impetus to rely on them. But that's not something we can really save in the Web PKI's current state.)
> But that's not something we can really save in the Web PKI's current state.
I agree with your assessment but it's not an excuse to give up without trying. I hope this is just because I'm not looking in the right places, but I don't see people trying.
What really makes me salty is that there was enough energy to mess with the rules around EKU, the primary effect of which is that non-browser software is now starting to just ignore the EKU bits. Even if it would've amounted to nothing, I'd really rather that effort had gone into NCs.
I think a lot of people have tried! The reason EKUs stuck where NCs haven’t is because EKU rules are simple (in relative terms) and OpenSSL didn’t make as much of a mess out of them.
I can't help but read your post as "OpenSSL didn't make a mess of EKUs so the CA/B had to fill that role instead" :/
(I really am salty about the EKUs. In a few years the EKU field will just be useless, due to operational annoyance driving devs to ignore it. Except in browsers of course.)
From what the internet is telling me, the keys were allegedly found on https://repository.emsign.com/certs/<redacted>.crt
Which, if true, is definitely a lot of fun.
Hope you people are ready for lots and lots of suddenly hackable IoT.
__
Edit: I might also be misinterpreting what I am seeing and it's actually weak logic that created the keys, in the sense that one could guess the private key?
Someone actually qualified please give credible answers.
I'm just pretending.
I think you’re right. And since the intermediate certs expire around 2039 and the private keys are known, we have plenty of smooth MitM fun against IOT in front of us.
> I think it's worth noting that this compromise is much worse than the private keys simply being stolen by a researcher. They are inherently weak single-byte keys that anyone can factor, and the issue cannot be contained.
The Go and Rustls upgrades specifically block the intermediate certs because neither of these use the system revocation lists, I believe. Once you upgrade to a trust store without the root cert for the CA this will also solve the issue. Not sure about other ecosystems.
Linux - the platform which offers no ability to revoke an intermediate certificate, thus necessitating every certificate library to implement its own blocking?
Windows is already blocking the compromised CAs as of today with no need for users to upgrade anything.
Every certificate library has to implement its own blocking no matter which platform you run on. Windows provides an API to do this at the system level, which means nothing if a given application vendors their own TLS library.
It's uncommon on Windows for applications to use a third party certificate verification library because Windows provides an API that does it. On Linux, you have no choice because all the platform provides is a bundle of PEM certificates.
> uncommon on Windows for applications to use a third party certificate verification library
I bet you have at least one copy of OpenSSL on your Windows system, probably multiple. Using the Windows native APIs is work. OpenSSL just works everywhere.
(Also, "the platform" doesn't technically even provide the cert bundle, depending on exact distro & packages.)
In that case it was ssh sessions being intercepted.
But my question is if a tor exit node or a vpn provider or your internet provider has a private key to any CA then can they mitm any normal web traffic even though it will show up as https without warnings in your browser?
Just wrote up a quickie about how Nix + LLMs make patching everything super simple via overlays. Simplest security response I've ever done in my life. http://ghuntley.com/patch
If you're responsible for PHP client software, and waiting on composer/ca-bundle to release a new update, be aware that https://github.com/paragonie/certainty has been updated with the 2026-10-20 bundle already.
This is so blatently terrible, its hard to imagine they won't be permenantly removed from the CA ecosystem. I'm pretty sure other CA's have been removed for less.
Previously such incidents have lead to the CA business cessation by the involved entities (e.g. Diginotar case). I dont see how it would be different in this case.
they will have to file an incident report, which will be heavily scrutinized, and can possibly (edit: i am leaning towards likely, as more information comes to light) result in their ejection from most/all root stores.
> An attacker with the private key of any of the compromised intermediate CAs could impersonate any website or service.
And how many more times do we need to read this before we replace Web PKI with a system that isn't as completely insane?
We already have a functioning system for delegating domain ownership in a hierarchical fashion where compromises are limited to only the subtree under the compromised entity. Let's start using it for domain validation sooner rather than later.
It's been obvious for a while now that root-of-trust schemes create juicy targets, and that juicy targets attract all sorts of bad behavior that wouldn't be economical if we used a web-of-trust.
Building a web-of-trust scheme that works might not be easy, but also it's not like we've been trying exceptionally hard lately either.
Web-of-trust doesn't work. Even before the PGP web-of-trust broke down several years ago, analyses of how the web-of-trust actually ended up working out showed that it basically boils back down to CAs: people rely on a few highly central keys to do most of the signing rather than signing keys themselves, and these keys effectively function like CAs.
The broader issue is that users don't want to (and probably don't have the ability to) actually make any trust decisions; they much prefer to delegate all of the decisions on trustworthiness to somebody else. The PKI root CA system does have its flaws, but on the whole, I suspect that people like Mozilla are better stewards as to whether or not the person vouching for somebody else is trustworthy than the average or even the above-average user.
Web of trust has been working between humans for over a million years. If we've failed to make computers do it, it's probably just for lack of trying.
To your second point, that might be true in a world where the consequences of making a bad trust decision was some kind of hassle related to changing passwords or reporting your cards stolen. But we seem to be moving towards a world where it lands you in a detention facility or some other dire consequence. I think that sooner or later, users are going to realize that they want that control and will be willing to do the corresponding trust hygiene work. Besides, isn't making that kind of work easy the point of technology? We just need to do better re: making it usable rather than investing in systems we know to be unsafe.
DANE replaces this system with one that has the same basic cryptographic properties, but in which you can't eject bad actors --- or even monitor them with a mandatory transparency log. It's strictly worse than this.
Maybe if people implemented name constraints and the CA/B forced CAs to use them. But not as it is; unconstrained sub-CAs are a scourge on the Web PKI.
I like constraints too, but listen carefully to EKR and 'agwa on this, because a lot of things that seem like straightforward fixes are much more complicated in reality. The most important thing I want from the WebPKI is expensive entry and the death penalty for fuckups, and I think we basically have that now.
It has the property of aligning cryptographic authentication with the domain name hierarchy. Yes, you trust the hierarchy. You trust LE too, so what? We need to move away from any authority being able to authenticate anyone, and DNS naturally aligns with the goal.
You've been vocal for a long time against DNSSEC deployment too for no discernable reason.
Why are you against every single thing that tries to make DNS useful for securing anything?
Do the words "no discernible reason" just mean something very different to you than they do to me? Because I've written somewhere in the vicinity of 100,000 words about the problems of DNSSEC over the last 20 years. My written DNSSEC critique predates HN itself.
This particular issue has nothing to do with "aligning authentication with the name hierarchy". The exact same thing that happened to EMudhra could happen to any TLD operator. The difference is that we have essentially no recourse when that happens, and far less ability to detect malfeasance.
People have debated DANE endlessly here, so I'm not sure how much more I have to add at this point. However, browsers, at least, do swiftly handle revocation for CAs, as indicated in this comment: https://news.ycombinator.com/item?id=50167244. They also handle EE revocation to varying extents, with Firefox having complete coverage and other browsers having partial coverage.
trying to understand where this service is mainly used. judging by a quick google search ...
is this related to Government of India related websites and their services/websites like tax filing etc? is the impact expected to be concentrated around indian citizens availing these services?
It doesn't have to, you can set X509 name constraints which say "the CA may only issue/may not issue certificates for these Subjects," or you can set CAA in DNS, for example.
(Of course, the former isn't really intended to constrain trusted Root CAs, moreso internal PKIs. But it is an option people should know about!)
Wow, Thanks for digging up/working out that support list! Actually a glint of hope.
…but, yeah, the issue is on layer 9. Even just nailing sub-CAs to ccTLDs breaks the moment a marketing person registers a .lol domain.
Then again, the CA/B is essentially a layer 9 entity. I just refuse to believe this is an unsolvable problem (though it might need NCv2 with a whole bunch more shit to cover more human creativity in policymaking.)
Yes and NO. These are intermediate CA's and for them to be recognized by your browser or system, they need to be signed by another CA or root certificate that your system already trusts.
SO, not all CA's are signed by root certificates already on your machine
You can pin, but almost nobody does (and half the world that does pin is probably pinned to Let's Encrypt).
Those who manage the root domains should have been able to pin who they trust, and then if you WANTED to you could add someone beyond what .com or .egg or .muffin lists.
https://kagi.com/search?q=dns+CAA CAA is one way, but you can also pin the actual certificate or certificate chain (which has its downsides, mind you).
Web PKI is cursed. Why should anyone have to ship a new version of Go, Electron, webpki-roots, etc. (possibly over a now-compromised TLS connection!) just to revoke a certificate? Why are so many packages independently shipping high-sensitivity trust-bootstrap credentials? And why can any CA still vouch for any domain instead of each being limited to a specific ccTLD or other non-total shard of subject names?
Also, it's quietly, in the email space, that we're seeing real innovation while browser vendors just say "no" to everything. We should be distributing trust, not centralizing it in browser vendor security teams and Let's Encrypt.
Web PKI doesn't mandate that every client ship with its own root certs. The clients you listed can be configured to use a centrally managed trust store, if that's what you want. The fact that they don't by default is a deliberate tradeoff that the clients made, not some standard's fault.
This isn't, like, one misbehaving client. It's the way the ecosystem has evolved. GP didn't specify whether they were criticizing the standard or the ecosystem more broadly, but even if they were criticizing the standard, it's pretty fair to evaluate a standard at least partly based on how it gets implemented in practice. There's a reason cryptography tools for the last decade or more have been focused on being misuse-resistant.
There is no one ecosystem. The world of web clients is highly diverse. Expecting every client implementation out there to converge onto one particular trust store is, first of all, magical thinking, but second of all, it reintroduces the single point of failure that web PKI is meant to avoid. The OS trust store is just one of many possible trust stores, there's nothing ordained about it. The problem is not with some standard, it's with a mistaken pre-conceived notion that there must only be one.
Many web clients have chosen to default to trust stores within their own ecosystem for usability and reproducibility reasons. When I as a user run "pip install requests", I expect to be able to issue HTTPS requests. I do not expect an implicit system dependency on ca-certificates - that might not even exist on my system!
If you want all of the web clients on your system to use a centrally managed trust store, then it's your responsibility to (a) know and enforce what clients exist on your system and (b) configure them all to use that trust store.
I'm not making an argument for a single centrally-managed trust store. The thing that seems most obviously bad to me here, as a non-crypto-expert, is that any CA can issue a certificate for any domain. This is probably made worse because there are hundreds of CAs, and AFAICT functionally every trust store trusts all of the same ones.
I don't know how we fix this, but it does seem like a big problem.
Yes. I am criticizing the de facto web PKI, not the somewhat better design intent. The design intent is still bad though: we should never have given CAs universal issuance privileges.
The web has continued to go the wrong way in practice. (For example, browser makers rejected RFC9102 DNSSEC stapling, which could have enabled an incremental migration away from CA-centric hell.) Everything fix the existing web PKI community makes just seems to centralize trust more.
For example, Let's Encrypt has been useful for moving people off unencrypted services, but side it's now ubiquitous on the internet and had to work within the broken universal-grant CA model, it now represents a terrifying central point of failure. Had browser makers supported DANE instead, and had we embraced DNSSEC instead of casting aspersions on it, we wouldn't have needed Let's Encrypt because ownership of a domain name would have already, by that very fact, let you authenticate to anyone.
> The design intent is still bad though: we should never have given CAs universal issuance privileges.
This is sort of right and sort of wrong. It's true that you could have a DNSSEC-style regime where only one entity could issue for a given domain, but as long as you're going to allow third party issuance at all, then you have to contend with the fact that most CAs want to issue in the big gTLDs (.com, .org, etc.) and so narrowing issuance doesn't help that much in many cases.
> Had browser makers supported DANE instead, and had we embraced DNSSEC instead of casting aspersions on it, we wouldn't have needed Let's Encrypt because ownership of a domain name would have already, by that very fact, let you authenticate to anyone.
This is ahistorical. By the time that DANE was designed, the WebPKI model was well entrenched and there was a huge population of browsers that couldn't really be upgraded and also only supported the WebPKI. If you wanted something that was acceptable to those browsers, it had to be WebPKI and it had to be cross-signed, hence Let's Encrypt.
I suppose you could argue that at some point after that one could have tried to deploy DANE and phase out LE and the rest of the WebPKI. I don't think that's true for the reasons that have been discussed on HN about DNSSEC, but that's really not the same as you wouldn't have needed LE in the first place.
> Had browser makers supported DANE instead, and had we embraced DNSSEC instead of casting aspersions on it, we wouldn't have needed Let's Encrypt because ownership of a domain name would have already, by that very fact, let you authenticate to anyone.
Had we been using DANE instead of WebPKI, the response to this sort of compromise would be "aw, shucks, someone proved to be untrustworthy and they're in such a critical role in the ecosystem that there's no way to route around this DNS provider being untrustworthy."
DNSSEC key rollovers don't change who has custody of the keys. They're not a magic spell that fixes stuff like this. It is closer to the truth that DNSSEC is limited to recovery from incidents like this to doing rollovers, rather than immediate revocations. Rollover is not something that makes DANE more attractive here.
Since I haven't seen this mentioned enough yet:
The private key for all 8 "compromised" CAs is a single byte: https://mastodon.catgirl.cloud/@49016/117474217042191790
One of the private keys is literally "4".
I'm putting "compromised" in quotes here, because I can't call it that without cringing and cursing.
[cf. also: https://news.ycombinator.com/item?id=50169109]
Is this real? This seems so ridiculous it makes me wonder for how long this CA has been in circulation in systems and if it has been exploited by someone previously discovering it in that time (state level actor or not). My old phone running Android 6 does not have any certificate from EMudhra, at the very least.
Apparently they've only been included in early October https://www.mail-archive.com/dev-security-policy@mozilla.org...
Almost certainly noticed and quietly exploited by a state actor
The Web PKI uses certificate transparency, so we’ll have a definitive answer about whether this is/was exploited soon.
(But in any case, CT ensures that it can’t be “quiet.”)
There were no certificates from the compromised intermediates logged to CT prior to remediation by the browsers.
CT is great for browsers. Largely irrelevant for anything being fetched outside of a browser.
That’s why I’m talking about it purely in the context of incident response/forensics.
You claimed CT would definitely prove whether it has or has not been exploited, which is false.
The lack of CT entries only proves that (most likely) browsers were not MITM’d.
There are plenty of ways you would never be able to tell if a fake cert had been generated and used via this attack vector (let's ignore validation attacks):
1. CT does not do anything if a state actor demands a CA in its borders generate a cert without publishing to the CT logs (or a three-letter-agency doing this illicitly). They can put SCTs in the cert, and still not publish to the logs, nobody is auditing the logs for every cert every browser sees.
2. Browsers won't check for SCTs in certs if they come from a private CA. you can MITM any domain through ZScaler all day long and nobody will notice
3. Wildcard certs make it easy to make/renew a cert that looks normal but hides requests on new/different hosts
4. Non-Browsers do not validate SCTs
I feel somewhat confident in speculating that a bunch of people at large companies will, in fact, be auditing the logs following this. That’s their main value; they’re not really an online/active prophylactic.
Nope. You can find this from the Chrome Root Program.
> Because no TLS certificates chaining to these six intermediate CAs were logged to CT prior to our CRLSet block on October 17, no fraudulent certificates issued by these CAs could have been trusted by default in Chrome or other CT-enforcing browsers.
A grumpy state actor today.
I believe these intermediates chained up to a third party root.
They chain up to emSign & Comodo:
https://groups.google.com/a/mozilla.org/group/dev-security-p...
To be clear, emSign is another name for EMudhra, and Comodo is now known as Sectigo. (You can't just look at the organization name in a certificate subject; you have to consult the CCADB: https://www.agwa.name/blog/post/the_certificate_issuer_field...)
Since they are also a root CA, are they allowed to audit themselves, or do the browser root programs require third-party audits?
I can't imagine one part of a business being on the up and up, and the guys down the hall running completely rogue.
Argh. Thanks for clearing that up.
It's real.
Yikes. I’d have to wonder if this CA should even be trusted ever again?
Definitely not. Their CPS requires that these keys be generated by an HSM and no HSM would ever generate these, so there's little reason to believe they're following any of their other controls.
it should not
chosen by fair dice roll, no doubt
https://xkcd.com/221/
Given that 4 is the value shown in this well known XKCD panel, it almost seems like a (im)practical joke or trolling.
I am shocked that one of the private keys was literally “4”. Anyone could have broken into this. I really hope there is an industry-wide effort to stop things like this in the future.... but I doubt it.
There is a variety of projects and researchers scanning for weak keys; possibly that's how this was found (haven't seen anything on that). These certs existed for a year and a half; that's bad but could be worse still.
One of the issues with sub-CAs (well, X509 certs in general) is that they can be ghosts in that there's no way you'll ever get it as a response on a TLS connection, so automated scanners on that won't find it.
CT should cover this (i.e. expose the cert so you can check for weak keys), but I have no idea if/how CT works for sub-CAs. [ed.: see below, doesn't seem to be in CT]
My understanding is that if something, like a browser, connects to a SSL site, they will either have or can obtain, one way or another, a complete chain all the way up to the root, so there can be no "ghost" certificate. And I would imagine a scanner could do all those same steps, and thus access all the same certs.
Is this a deficiency in scanner software? You seem to indicate it is a fundamental weakness in X509; I'm just trying to understand what.
Could you maybe describe a specific example of what you're describing?
In the most extreme case, you can just issue a certificate and not use it anywhere. If it leaks, it's still a security issue, because it's valid.
More realistically, especially with sub-CAs, they might only be used on e.g. corporate networks. TLS scanners may not be able to reach any of the hosts that uses such a cert. As the sibling post points out, clients checking for the cert in Certificate Transparency logs counters that (adding a requirement that the cert be publicly known, which TLS/X509 by itself very much does not have) — but of course this only helps if your client does CT…
Ah okay, thanks. So to be concrete, something like automation running 'curl' on an internal network might see the full chain, including the weak cert, and be vulnerable, but scanners on the wider internet won't see it. I was confused by "...there's no way you'll ever get it as a response on a TLS connection..." — I guess you just meant a _public_ TLS connection. Or it could be otherwise installed on corporate machines' local cert bundles.
If you're doing a MITM attack, you can selectively intercept certain clients, and only serve the compromised certificate in those cases only. Automated scanners won't pick that up. None of this actually works though, because browsers started mandating certificate transparency.
For their own stuff, Mozilla has talked in the past about specifically just only trusting intermediates they've seen. Their modern root agreement says the CA will disclose all relevant intermediates, so arguably they have a complete list and further if that CA "forgot" about a few of them whether that's because your firm is too disorganised ("Oh, right, the one on Barry's laptop, forgot that one") or an actual attempt to sidestep this rule - then we certainly don't want to trust these undisclosed intermediates, do we ? They're either purposefully shady, or they're forgotten about and likely never have been audited.
Y'know… let's just check…
https://ctlogs.io/search?mode=fingerprint&q=42c4accd12c4f595...
https://ctlogs.dev/search?q=42C4ACCD12C4F59597925E1A08A7A901...
https://ctlogs.io/search?q=EBED6475C2C2D80FCB199F3FE8DD6E6B3...
https://ctlogs.dev/search?q=EBED6475C2C2D80FCB199F3FE8DD6E6B...
Nothing for "CN=EM DV TLS CA - G3B,O=eMudhra BV" (not sure which sha256 this uses, 2nd is the spki sha256)
I should be clear here my understanding is/was these are sub-CAs. Apparently they're (trying to be?) roots themselves? The point of logging a root cert in CT is somewhat moot… though tbh I would argue anything issued by a CA should be in CT logs, even cross-signing another CA that is becoming a root itself.
Of all the things... i never expected there to be an XKCD for this: https://xkcd.com/221/
They used the xkcd PRNG: https://xkcd.com/221/
4 is as likely as any other randomly chosen number over a given range.
The impact of this incident is very unevenly spread.
Over 10 years ago, Mozilla shipped OneCRL [1]. We remediated this incident in a couple of hours for Firefox users who were protected automatically without the need for updates. Chrome, Apple and Microsoft have similar tooling. Since then, we've built more advanced tooling to handle revocation at scale for leaf certs (CRLite [2]).
However, for the rest of the ecosystem, there has been little to no investment in revocation and for those clients, this is a massive problem. Hopefully, we'll see folks invest now. Efforts like upki [3] look promising.
[1] https://blog.mozilla.org/security/2015/03/03/revoking-interm...
[2] https://hacks.mozilla.org/2025/08/crlite-fast-private-and-co...
[3] https://github.com/rustls/upki
Firefox Mobile 158.0 on Android 17 (Pixel 7) connects to all the demo sites with zero warnings. Any idea why the "automatic protection without updates" doesn't seem to be working with that combination?
I am seeing the same thing in the beta app (159.0b4) on an identical device. The sites are blocked correctly in Chrome.
Pixel 10 with 158.0.1 still connects to the emSign ones, even though the patch notes for 158.0.1 mention that it updates the CRL for those without 'Remote Improvements' enabled?
edit: Disabling all the eMudhra CAs in Android settings does nothing, cool?
edit: I guess there's no way to manually ask for CRL update, cool??
edit: Gave up and reinstalled Firefox. Seems to be fine now.
I'm on the same Firefox version on android and they are blocked now
On my just updated Firefox 158.0.1 on Android they are not blocked.
Edit: however on Firefox Focus 157.0.1 they are blocked.
More on upki:
https://discourse.ubuntu.com/t/an-update-on-upki/77063
My interest in building OneCRL support into upki has definitely increased this week. Issue:
https://github.com/rustls/upki/issues/229
I'm hoping some organizations will step forward to fund work on this.
(Note that curl on Ubuntu 26.10 now has CRLite support baked via upki -- unfortunately that doesn't help with this because AIUI CRLite is only for end entities, not for intermediate certificates.)
It's very inconsistent for me even on just Firefox. On multiple systems running different instances of Firefox, checking with https://emudhra.we-have-a-problem.com/:
One blocks everything; one blocks 6 out of 12; one blocks the other 6 out of 12; one blocks nothing.
You mean you and Chrome stopped supporting normal CRLs and OCSP, replacing (for normal users) these distributed-trust technologies with central lists controlled by browsers
There is a good reason they did. CRL and especially OCSP are both terrible and not particularly effective
You mean the response was uneven. The impact was a complete and total potential compromise of literally everyone. Every domain. Every client using one of the public root programs. Every user of those clients.
I mean, it's an emergency, but the acute severity is debatable; many times a month the major browsers quietly deal with vulnerabilities that yield attackers direct control of victim computers; here, attackers get the ability to spoof websites if they're in a position to hijack connections.
The middlebox situation, with non-updatable roots, is very annoying. But middleboxes also have unfixable RCEs, so...
It's totally fair to evaluate different projects by how well positioned they are to update their WebPKI trust anchors. I'm just saying, keep perspective.
So it other words, it allowed attackers to do the one thing that Web PKI is supposed to prevent.
Being able to quickly update trust roots is at best a hack to paper over the issue when there is no good reason why every podunk CA should have authority to generate certificates for every domain in the first place. It's an inexcusable design flaw. Or a feature that gives power to root stores at the expense of everyones security, from the perspective of the root store operators.
Ok, now do that same paragraph, but for drive-by RCE vulnerabilities.
Nobody thinks this is a good thing. It's bad. Hopefully, eMudhra gets distrusted. We've done that to bigger CAs.
Keep in mind that a _lot_ of software out there uses TLS as its only trust anchor for updates, commands or similar.
This can and will be weaponized for take-overs of systems. They will be of the consumer kind, but they will also be of the industry kind. Let's pray that they will not be of the state or military kind.
Here's a question for Mozilla et. al.:
It's cute you have a magic DIY CRL. You accepted these assholes into your root program.
They lost the KEYS.
What is the screening process for CA's that can't be bothered to use a HSM?
Even Honest Achmed wasn't this careless.
>What is the screening process for CA's
it's done in the open, and you're even allowed to voice your cute opinion during the multi-week public commentary periods.
here is an overview https://wiki.mozilla.org/CA/Root_Inclusion_Overview
IIRC up until very recently the screening process was "they report that they're good boys."
The screening process has been more involved in that since around the late 2000's. I wouldn't call 20 years "very recently," especially in the context of the history of the web.
They didn't lose the keys, a sub-CA did.
Which is to say, sub-CAs in itself are a giant loophole that needs plugging. Especially since AFAIK nobody is bothering with name constraints (RFC5280 section 4.2.1.10).
eMudhra is also a root CA operator. One root CA operator cross-signing another root CA operator is a good thing actually, and it's what allowed Let's Encrypt to work before their root certificate was widely trusted.
Issuing sub CAs to non-root operators has historically been a big loophole though it's not as bad these days since multiple root programs now require approval before CAs can do it.
Didn't Let's Encrypt have to jump through all sorts of hoops to prove they were competent and trustworthy before that happened?
Now it's coming out these guys used "4" as a private key. That's a crazy amount of incompetence and malfeasance. Did they vibe-code a CA? HOW DOES THIS HAPPEN? I am dumbfounded.
You couldn't even do this if you installed Microsoft Small Business Server 2008 today, unpatched, with the CA on default settings.
eMudhra had to jump through even more hoops.
Obviously the system failed here, but it's a failure of a root certificate operator, not a sub-CA operator as claimed by eqvinox.
The situation is even worse than I thought.
They hold intermediate certificates issued by TWO different root CAs, neither of which they operate.
So two separate entities didn't bother to read their certificate policy or inspect their operations. Have we not learned anything from past mistakes?
Roots should be responsible for all their sub-CAs, full stop. If they don't trust them enough to accept that responsibility, then the system is broken.
The reason nobody bothers with NCs is because they don't work very well in practice. They also have their own baroque matching rules that are not intuitive if you're from the land of UNIX globs.
(In fairness this is a self-fulfilling prophecy: a lot of validators handle NCs poorly or not at all, so there's no impetus to rely on them. But that's not something we can really save in the Web PKI's current state.)
> But that's not something we can really save in the Web PKI's current state.
I agree with your assessment but it's not an excuse to give up without trying. I hope this is just because I'm not looking in the right places, but I don't see people trying.
What really makes me salty is that there was enough energy to mess with the rules around EKU, the primary effect of which is that non-browser software is now starting to just ignore the EKU bits. Even if it would've amounted to nothing, I'd really rather that effort had gone into NCs.
I think a lot of people have tried! The reason EKUs stuck where NCs haven’t is because EKU rules are simple (in relative terms) and OpenSSL didn’t make as much of a mess out of them.
I can't help but read your post as "OpenSSL didn't make a mess of EKUs so the CA/B had to fill that role instead" :/
(I really am salty about the EKUs. In a few years the EKU field will just be useless, due to operational annoyance driving devs to ignore it. Except in browsers of course.)
I've opened up a PR adding an example certificate generated using these keys to https://badssl.com - https://github.com/chromium/badssl.com/pull/559
From what the internet is telling me, the keys were allegedly found on https://repository.emsign.com/certs/<redacted>.crt
Which, if true, is definitely a lot of fun.
Hope you people are ready for lots and lots of suddenly hackable IoT.
__
Edit: I might also be misinterpreting what I am seeing and it's actually weak logic that created the keys, in the sense that one could guess the private key?
Someone actually qualified please give credible answers. I'm just pretending.
> Hope you people are ready for lots and lots of suddenly hackable IoT.
I was not expecting to find a silver lining _this bright_ but you have a point.
I think you’re right. And since the intermediate certs expire around 2039 and the private keys are known, we have plenty of smooth MitM fun against IOT in front of us.
Source? That would be an incredible blunder, but that also appears to be the kind of URL one would expect to find certs at.
https://mastodon.catgirl.cloud/@49016/117474217042191790
Apparently it's even worse
That's actually a good point - tons of IoT is "secure enough" to sign things, but not secure enough to bother pinning anything ...
Also who hasn't left their private keys hanging around web-accessible, eh? lol
https://chaos.social/@fluepke/117474156947559280
Private keys can be trivially recovered from the public keys because they're tiny. I found D=156, flüpke found D=4.
Yes, that's the entire private key.
all of them:
4, 56, 66, 115, 155, 156, 230, 237
This is potentially a better link from the Mozilla bug tracker: https://bugzilla.mozilla.org/show_bug.cgi?id=2083449
This seems like an AI-generated summary and it leaves some obvious questions unanswered.
This thread (linked by the page) seems like a better source: https://groups.google.com/a/mozilla.org/g/dev-security-polic...
Ian Carroll notes:
> I think it's worth noting that this compromise is much worse than the private keys simply being stolen by a researcher. They are inherently weak single-byte keys that anyone can factor, and the issue cannot be contained.
Running Go? Upgrade to 1.27.3 or 1.26.10.
Rust with rustls? Upgrade to rustls-webpki 0.103.16 and/or webpki-roots/webpki-root-certs 1.0.10.
Python? Upgrade certifi to 2026.10.19.
Homebrew ca-certificates? 2026-09-25_1.
Electron? 44.9.1, 43.8.1, or 42.11.16.
The Go and Rustls upgrades specifically block the intermediate certs because neither of these use the system revocation lists, I believe. Once you upgrade to a trust store without the root cert for the CA this will also solve the issue. Not sure about other ecosystems.
Windows? Upgrade to Linux.
Linux - the platform which offers no ability to revoke an intermediate certificate, thus necessitating every certificate library to implement its own blocking?
Windows is already blocking the compromised CAs as of today with no need for users to upgrade anything.
Every certificate library has to implement its own blocking no matter which platform you run on. Windows provides an API to do this at the system level, which means nothing if a given application vendors their own TLS library.
It's uncommon on Windows for applications to use a third party certificate verification library because Windows provides an API that does it. On Linux, you have no choice because all the platform provides is a bundle of PEM certificates.
> uncommon on Windows for applications to use a third party certificate verification library
I bet you have at least one copy of OpenSSL on your Windows system, probably multiple. Using the Windows native APIs is work. OpenSSL just works everywhere.
(Also, "the platform" doesn't technically even provide the cert bundle, depending on exact distro & packages.)
Also on front HN page is https://kaba.cx/posts/20261020_Tor/ on how 300 tor exit nodes were compromised.
In that case it was ssh sessions being intercepted.
But my question is if a tor exit node or a vpn provider or your internet provider has a private key to any CA then can they mitm any normal web traffic even though it will show up as https without warnings in your browser?
Yes.
Just wrote up a quickie about how Nix + LLMs make patching everything super simple via overlays. Simplest security response I've ever done in my life. http://ghuntley.com/patch
If you're responsible for PHP client software, and waiting on composer/ca-bundle to release a new update, be aware that https://github.com/paragonie/certainty has been updated with the 2026-10-20 bundle already.
https://chaos.social/@fluepke/117474156947559280
D=4. That's the entire private key for one of the certs.
are there any consequences to eMudhra?
This is so blatently terrible, its hard to imagine they won't be permenantly removed from the CA ecosystem. I'm pretty sure other CA's have been removed for less.
That would damage public perception of the current Indian government, so the administration will do everything to keep the CA afloat.
Previously such incidents have lead to the CA business cessation by the involved entities (e.g. Diginotar case). I dont see how it would be different in this case.
I hadn't heard of the CA before and had to look it up. They're a publicly listed company in India. Markets will price this in.
https://www.nseindia.com/get-quote/equity/EMUDHRA/eMudhra-Li...
they will have to file an incident report, which will be heavily scrutinized, and can possibly (edit: i am leaning towards likely, as more information comes to light) result in their ejection from most/all root stores.
This probably has an unimaginable blast radius of existing software out there.
So uh, for various IOT junk like Smart TVs, does that mean the ones that don't get security updates (pretty much all of them) are permanently pwned?
> What are the consequences?
> An attacker with the private key of any of the compromised intermediate CAs could impersonate any website or service.
And how many more times do we need to read this before we replace Web PKI with a system that isn't as completely insane?
We already have a functioning system for delegating domain ownership in a hierarchical fashion where compromises are limited to only the subtree under the compromised entity. Let's start using it for domain validation sooner rather than later.
>And how many more times do we need to read this before we replace Web PKI with a system that isn't as completely insane?
You say this like it's easy and simple and we are simply not choosing to do so.
It's been obvious for a while now that root-of-trust schemes create juicy targets, and that juicy targets attract all sorts of bad behavior that wouldn't be economical if we used a web-of-trust.
Building a web-of-trust scheme that works might not be easy, but also it's not like we've been trying exceptionally hard lately either.
Web-of-trust doesn't work. Even before the PGP web-of-trust broke down several years ago, analyses of how the web-of-trust actually ended up working out showed that it basically boils back down to CAs: people rely on a few highly central keys to do most of the signing rather than signing keys themselves, and these keys effectively function like CAs.
The broader issue is that users don't want to (and probably don't have the ability to) actually make any trust decisions; they much prefer to delegate all of the decisions on trustworthiness to somebody else. The PKI root CA system does have its flaws, but on the whole, I suspect that people like Mozilla are better stewards as to whether or not the person vouching for somebody else is trustworthy than the average or even the above-average user.
Web of trust has been working between humans for over a million years. If we've failed to make computers do it, it's probably just for lack of trying.
To your second point, that might be true in a world where the consequences of making a bad trust decision was some kind of hassle related to changing passwords or reporting your cards stolen. But we seem to be moving towards a world where it lands you in a detention facility or some other dire consequence. I think that sooner or later, users are going to realize that they want that control and will be willing to do the corresponding trust hygiene work. Besides, isn't making that kind of work easy the point of technology? We just need to do better re: making it usable rather than investing in systems we know to be unsafe.
Humans are generally considered to have been around for only ca. 300'000 years.
Also, the interpersonal web of trust is IMHO quite clearly failing in the age of mass media, and not just recently.
> We already have a functioning system for delegating domain ownership in a hierarchical fashion
Well, yeah. DANE should have won. NameConstraints would be nice tooo, but who's going to make CAs use it?
And FFS, clients could at least check CRLs once in a while.
DANE replaces this system with one that has the same basic cryptographic properties, but in which you can't eject bad actors --- or even monitor them with a mandatory transparency log. It's strictly worse than this.
> It's strictly worse than this.
Maybe if people implemented name constraints and the CA/B forced CAs to use them. But not as it is; unconstrained sub-CAs are a scourge on the Web PKI.
I like constraints too, but listen carefully to EKR and 'agwa on this, because a lot of things that seem like straightforward fixes are much more complicated in reality. The most important thing I want from the WebPKI is expensive entry and the death penalty for fuckups, and I think we basically have that now.
It has the property of aligning cryptographic authentication with the domain name hierarchy. Yes, you trust the hierarchy. You trust LE too, so what? We need to move away from any authority being able to authenticate anyone, and DNS naturally aligns with the goal.
You've been vocal for a long time against DNSSEC deployment too for no discernable reason.
Why are you against every single thing that tries to make DNS useful for securing anything?
Do the words "no discernible reason" just mean something very different to you than they do to me? Because I've written somewhere in the vicinity of 100,000 words about the problems of DNSSEC over the last 20 years. My written DNSSEC critique predates HN itself.
This particular issue has nothing to do with "aligning authentication with the name hierarchy". The exact same thing that happened to EMudhra could happen to any TLD operator. The difference is that we have essentially no recourse when that happens, and far less ability to detect malfeasance.
People have debated DANE endlessly here, so I'm not sure how much more I have to add at this point. However, browsers, at least, do swiftly handle revocation for CAs, as indicated in this comment: https://news.ycombinator.com/item?id=50167244. They also handle EE revocation to varying extents, with Firefox having complete coverage and other browsers having partial coverage.
trying to understand where this service is mainly used. judging by a quick google search ...
is this related to Government of India related websites and their services/websites like tax filing etc? is the impact expected to be concentrated around indian citizens availing these services?
The way the web works, any CA (Certificate Authority) can create TLS certificates for almost any website.
This means that the people with these keys could MITM almost any https connection people make, not only the ones that this CA issued.
It doesn't have to, you can set X509 name constraints which say "the CA may only issue/may not issue certificates for these Subjects," or you can set CAA in DNS, for example.
(Of course, the former isn't really intended to constrain trusted Root CAs, moreso internal PKIs. But it is an option people should know about!)
To my knowledge, name constraints are very rare in actual use, and a bunch of implementations don't even support them. Am I wrong?
Rare in public PKIs, yes; not so much in private ones, I would imagine.
From my limited experience (using them at home) they seem to be fairly well supported in client libraries, actually!
- OpenSSL has full support, https://docs.openssl.org/master/man5/x509v3_config/
- GnuTLS has full support, https://www.gnutls.org/manual/html_node/X509-certificate-API...
- go (crypto/x509) supports everything except DirectoryName constraints, https://pkg.go.dev/crypto/x509#Certificate.Verify
- Python (pyca/cryptography) has full support, https://cryptography.io/en/stable/x509/reference/#cryptograp...
- Windows/Schannel has full support, https://learn.microsoft.com/en-us/windows/win32/seccertenrol...
- Java has full support, https://docs.oracle.com/en/java/javase/21/docs/api/java.base...
- I know that NSS also supports them from experience but (sorry!) couldn't find the docs in a few seconds of searching
- I know that Strongswan supports them well because I actually opened an issue about it a few years back and got it fixed :-)
(Just a few off the top of my head)
Wow, Thanks for digging up/working out that support list! Actually a glint of hope.
…but, yeah, the issue is on layer 9. Even just nailing sub-CAs to ccTLDs breaks the moment a marketing person registers a .lol domain.
Then again, the CA/B is essentially a layer 9 entity. I just refuse to believe this is an unsolvable problem (though it might need NCv2 with a whole bunch more shit to cover more human creativity in policymaking.)
Yes and NO. These are intermediate CA's and for them to be recognized by your browser or system, they need to be signed by another CA or root certificate that your system already trusts.
SO, not all CA's are signed by root certificates already on your machine
"any CA (Certificate Authority) can create TLS certificates for almost any website."
This has always been incredibly stupid.
You can pin, but almost nobody does (and half the world that does pin is probably pinned to Let's Encrypt).
Those who manage the root domains should have been able to pin who they trust, and then if you WANTED to you could add someone beyond what .com or .egg or .muffin lists.
> and half the world that does pin is probably pinned to Let's Encrypt
To be fair, unless I'm misunderstanding, wouldn't this be a good move?
LE has a good security record and takes itself seriously, versus these smaller CAs that seem to mess up regularly.
Why? How do you pin a website to a specific cert provider? And what happens when you want to switch?
https://kagi.com/search?q=dns+CAA CAA is one way, but you can also pin the actual certificate or certificate chain (which has its downsides, mind you).
Because it makes you only as secure as the the LEAST secure CA. Such as the really bad ones that don't use Hardware Security Modules.
It’s used by Indian companies and also they provide digital signature services. It’s a widely used platform.
Thanks Wayne.
Web PKI is cursed. Why should anyone have to ship a new version of Go, Electron, webpki-roots, etc. (possibly over a now-compromised TLS connection!) just to revoke a certificate? Why are so many packages independently shipping high-sensitivity trust-bootstrap credentials? And why can any CA still vouch for any domain instead of each being limited to a specific ccTLD or other non-total shard of subject names?
Also, it's quietly, in the email space, that we're seeing real innovation while browser vendors just say "no" to everything. We should be distributing trust, not centralizing it in browser vendor security teams and Let's Encrypt.
Web PKI doesn't mandate that every client ship with its own root certs. The clients you listed can be configured to use a centrally managed trust store, if that's what you want. The fact that they don't by default is a deliberate tradeoff that the clients made, not some standard's fault.
This isn't, like, one misbehaving client. It's the way the ecosystem has evolved. GP didn't specify whether they were criticizing the standard or the ecosystem more broadly, but even if they were criticizing the standard, it's pretty fair to evaluate a standard at least partly based on how it gets implemented in practice. There's a reason cryptography tools for the last decade or more have been focused on being misuse-resistant.
There is no one ecosystem. The world of web clients is highly diverse. Expecting every client implementation out there to converge onto one particular trust store is, first of all, magical thinking, but second of all, it reintroduces the single point of failure that web PKI is meant to avoid. The OS trust store is just one of many possible trust stores, there's nothing ordained about it. The problem is not with some standard, it's with a mistaken pre-conceived notion that there must only be one.
Many web clients have chosen to default to trust stores within their own ecosystem for usability and reproducibility reasons. When I as a user run "pip install requests", I expect to be able to issue HTTPS requests. I do not expect an implicit system dependency on ca-certificates - that might not even exist on my system!
If you want all of the web clients on your system to use a centrally managed trust store, then it's your responsibility to (a) know and enforce what clients exist on your system and (b) configure them all to use that trust store.
I'm not making an argument for a single centrally-managed trust store. The thing that seems most obviously bad to me here, as a non-crypto-expert, is that any CA can issue a certificate for any domain. This is probably made worse because there are hundreds of CAs, and AFAICT functionally every trust store trusts all of the same ones.
I don't know how we fix this, but it does seem like a big problem.
Yes. I am criticizing the de facto web PKI, not the somewhat better design intent. The design intent is still bad though: we should never have given CAs universal issuance privileges.
The web has continued to go the wrong way in practice. (For example, browser makers rejected RFC9102 DNSSEC stapling, which could have enabled an incremental migration away from CA-centric hell.) Everything fix the existing web PKI community makes just seems to centralize trust more.
For example, Let's Encrypt has been useful for moving people off unencrypted services, but side it's now ubiquitous on the internet and had to work within the broken universal-grant CA model, it now represents a terrifying central point of failure. Had browser makers supported DANE instead, and had we embraced DNSSEC instead of casting aspersions on it, we wouldn't have needed Let's Encrypt because ownership of a domain name would have already, by that very fact, let you authenticate to anyone.
> The design intent is still bad though: we should never have given CAs universal issuance privileges.
This is sort of right and sort of wrong. It's true that you could have a DNSSEC-style regime where only one entity could issue for a given domain, but as long as you're going to allow third party issuance at all, then you have to contend with the fact that most CAs want to issue in the big gTLDs (.com, .org, etc.) and so narrowing issuance doesn't help that much in many cases.
> Had browser makers supported DANE instead, and had we embraced DNSSEC instead of casting aspersions on it, we wouldn't have needed Let's Encrypt because ownership of a domain name would have already, by that very fact, let you authenticate to anyone.
This is ahistorical. By the time that DANE was designed, the WebPKI model was well entrenched and there was a huge population of browsers that couldn't really be upgraded and also only supported the WebPKI. If you wanted something that was acceptable to those browsers, it had to be WebPKI and it had to be cross-signed, hence Let's Encrypt.
I suppose you could argue that at some point after that one could have tried to deploy DANE and phase out LE and the rest of the WebPKI. I don't think that's true for the reasons that have been discussed on HN about DNSSEC, but that's really not the same as you wouldn't have needed LE in the first place.
> Had browser makers supported DANE instead, and had we embraced DNSSEC instead of casting aspersions on it, we wouldn't have needed Let's Encrypt because ownership of a domain name would have already, by that very fact, let you authenticate to anyone.
Had we been using DANE instead of WebPKI, the response to this sort of compromise would be "aw, shucks, someone proved to be untrustworthy and they're in such a critical role in the ecosystem that there's no way to route around this DNS provider being untrustworthy."
> aw, shucks, someone proved to be untrustworthy and they're in such a critical role in the ecosystem
You mean until the DNSsec key rollover completes and they're no longer in that role?
As opposed to what we have now, an indefinite period where crappy non-updated devices will still accept these certs and nothing can be done about it?
The Web PKI works great for browsers. Everything else, not so much.
(To be fair, the crappy devices¹ would probably fail to deal with the periodic DNSsec root key rollovers. But at least that's a fail-closed.)
¹ a label that includes older versions of systemd-resolved, for whatever that may mean
DNSSEC key rollovers don't change who has custody of the keys. They're not a magic spell that fixes stuff like this. It is closer to the truth that DNSSEC is limited to recovery from incidents like this to doing rollovers, rather than immediate revocations. Rollover is not something that makes DANE more attractive here.
Why don't these massive package managers use the host OS CA store, with an optional preconfigured "additional" store if clients need them?
Is the update cadence of CAs that different between the sources? Is the list of CAs included so different from OS vendors and the package managers?
Creating a dependency on OS specific APIs solves this one niche problem but causes a hundred more.
> Also, it's quietly, in the email space, that we're seeing real innovation […]
Can you elaborate on this innovation in the email space around PKI?