https://gist.github.com/AGWA/5a78186e0f4a7d537b8891a7b46f945... is the list of certificates in Certificate Transparency issued by the blocked CAs as of this time. They appear to be non-malicious test certificates, and the DNS name in the first certificate indicates who likely discovered the issue.
What's alarming and unprecedented is that yesterday, two Certificate Transparency log implementations were updated to block the logging of certificates issued by the CAs. This likely indicates total private key compromise, and the blocking by CT logs is to prevent the logs from being spammed by forged certificates. However, it also means there will be no place to record forged certificates found in the wild. (These certificates won't validate in CT-enforcing clients since they won't be in CT logs, but could be used to attack non-CT-enforcing clients.)
Am I off base, or should I be surprised that you were able to get the mentioned cert issued in the first place this recently (yesterday)? It seems unexpected that certificates are being actively issued and logged coming from a to-be-forcibly-distrusted part of the hierarchy.
The bugzilla issues mentioned elsewhere suggest at least a mostly orderly removal of trust with issuance stopped several months ago. Your new cert was issued by “CN=EM DV TLS CA - G3B,O=eMudhra BV,C=NL”, which presumably chains to the G3 root, and the bugzilla issue seems to say that G3 was going to be dropped from the root lists some time ago but that maybe it would be cross-signed by something still trusted. So I assume that something else is going on.
Was that cert issued via normal means (e.g. ACME)?
CT is for logging certificates from trusted CAs. Logging certificates from untrusted CAs is out of scope, and can be harmful as untrusted certificates could be used to spam the log until it's unavailable.
Of course, the notion of "trusted" is complicated. These CAs are no longer trusted by up-to-date clients, but out-of-date clients may continue to trust them. The needs of up-to-date clients take priority over the needs of out-of-date clients.
Those tickets sound fairly non-dramatic - a trusted root certificate was dual-use, in breach of root certificate policy, and have committed to transition to TLS-only certificates and remove trust in the old ones.
But the Go issue is market urgent, and assigns it a CVE, so clearly there's more to it than that.
It is a shame that you cannot have a cert signed by multiple CAs.
(The format seems like it would allow it, but nothing supports it, and in practice CAs demand the ability to actually modify some fields, and then sign that.)
It is done with intermediate certs, though! It's a common method of establishing trust in new root certs: sign the intermediate with an already-trusted root cert, then wait for the community to adopt the new root cert over the years.
For example, the initial Let's Encrypt Authority X3 was signed by both their own (new, not-yet-universally-trusted) ISRG Root X1, and the universally-trusted third-party IdenTrust DST Root CA X3.
One crucial detail is that it isn't the same certificate. Rather, it is two separate certificates which just so happen to be using the same key pair, so the leaf cert is in essence signed by both intermediate certs at once.
I wonder if it would be possible to do the same thing on your own, actually: can a server present two completely separate cert chains to a connecting client - as long as the leaves use the same key pair? Technically AFAIK the only requirements should be 1) the key pair in use for the connection matches the cert, 2) the domain matches the cert's Subject, and 3) the cert is trusted, so at first glance it might be possible...
Another option: Use ACME together with ARI (RFC 9773). The client checks ARI data every hour. If the cert needs to be replaced – for example like in this scenario – the CA will inform the client, which in turn would then request a new cert.
I know it’s not convenient to automate for every kind of device though. I guess in some of those cases it might be better to have a load balancer in front of the device. Or use an alternative PKI.
Every time there is a CA issue, someone comes up with "this would be so much better if we'd make it more complex than it already is, as it would make it a bit more convenient to deal with the most recent issue".
I don't think that's the right way to think about it.
I think certificates should be like badges that you can collect – the more badges the higher the trust. So if you are a French company, maybe the tax office in France can sign your certificate to show that you indeed is a real company. If you are accepting card payments – Visa and Mastercard could sign your certificate. If you have a domain the TLD owner could sign your certificate to show that it's indeed your domain… And so on…
And then the browser could present these badges in a nice way to the user.
I just worry that this would just bring us back to the: "Pay $$$$$$ for a certificate, those pesky lets encrypt free certs are not expensive enough to give trust", BS that always happens.
Yeah, that's one of the complications. It would have to be ignored in processing, or multiple variants be presented at once (preferred).
Certificates are not the same as the public key; multiple certs sharing the same key is essentially the way around this. It's not as elegant as identical signing of the same cert, but it could work.
Identical signing of the same cert also runs into issues like "who gets to decide the serial number" and "how to deal with revocation lists: all of, or any of?".
And turning fields like issuer and serial into arrays risks someone accidentally using index 0 for one field and index 1 for another.
Combine that with the insane back-and-forth nightmare that the issuance process would turn into, and I have a very hard time seeing the benefit in it. After all, nobody is stopping you from requesting multiple certs independently, watching the revocation logs, and switching to the backup when required.
I mean, they're the TLS certs are baked into the stdlib 'tls' package, not the compiler itself.
It's just an unfortunate unforced error that the go TLS package is bundled along with the compiler, in the same way Safari being bundled with iOS updates is an unforced error meaning a safari security bug requires a full OS update.
Oh, wow, that makes it even sillier. If I want to delete certs from my system certificate store, I can do that, the stdlib should not be making that choice if it's not even packaging the things.
These are intermediate certificates, and the system certificate store on Linux provides no way to tell verifiers such as Go's crypto/x509 that an intermediate is revoked. So Go really has no other option here.
It's probably about power. Certs control is getting higher value, so control over this policy means more negotiation power with whatever states (governments) need from platforms.
It's easy to imagine something like: "give us some grant taxpayers money and we'll add your cert to our trusted list/remove theirs cert/disable cert when run on this hardware/etc."
Clearly the platform isn't designed to do this. Nobody thought this was going to be a necessary facility. They have just crammed an array of numbers as literal values deep into the standard library. So clearly this is an exceptional event, and not the exercise of a feature that was foreseen.
I really appreciate Firefox to have their own certificate DB because it allows to create separate profiles with different trusted certificate sets. The country where I live issued it's own root certificates which I have reasons not to trust in all cases but when accessing government services etc. So I've created a separate Firefox profile where I've installed those malicious certificates, keeping the main Firefox profile clean.
It's nice that firefox implemented that but it's the wrong place to do it IMO. It's the sort of thing that should be built into the OS along with fine grained permissions and sandboxing. The browser is merely providing a bandaid over a deficiency.
Yes, as I understand it, this sort of problem is what “Name Constraints”[0] were designed to solve. (Well, really, they were intended to be used with corporate internal CAs[1], but there's no reason they wouldn't work more broadly, too.)
It's mostly historical. They used to suck in the past, but the implementations remain. Nowadays you are better off configuring to use OS certificates if possible.
What's alarming and unprecedented is that yesterday, two Certificate Transparency log implementations were updated to block the logging of certificates issued by the CAs. This likely indicates total private key compromise, and the blocking by CT logs is to prevent the logs from being spammed by forged certificates. However, it also means there will be no place to record forged certificates found in the wild. (These certificates won't validate in CT-enforcing clients since they won't be in CT logs, but could be used to attack non-CT-enforcing clients.)
The bugzilla issues mentioned elsewhere suggest at least a mostly orderly removal of trust with issuance stopped several months ago. Your new cert was issued by “CN=EM DV TLS CA - G3B,O=eMudhra BV,C=NL”, which presumably chains to the G3 root, and the bugzilla issue seems to say that G3 was going to be dropped from the root lists some time ago but that maybe it would be cross-signed by something still trusted. So I assume that something else is going on.
Was that cert issued via normal means (e.g. ACME)?
Of course, the notion of "trusted" is complicated. These CAs are no longer trusted by up-to-date clients, but out-of-date clients may continue to trust them. The needs of up-to-date clients take priority over the needs of out-of-date clients.
https://bugzilla.mozilla.org/show_bug.cgi?id=2083709
https://bugzilla.mozilla.org/show_bug.cgi?id=2018979
But the Go issue is market urgent, and assigns it a CVE, so clearly there's more to it than that.
(The format seems like it would allow it, but nothing supports it, and in practice CAs demand the ability to actually modify some fields, and then sign that.)
For example, the initial Let's Encrypt Authority X3 was signed by both their own (new, not-yet-universally-trusted) ISRG Root X1, and the universally-trusted third-party IdenTrust DST Root CA X3.
One crucial detail is that it isn't the same certificate. Rather, it is two separate certificates which just so happen to be using the same key pair, so the leaf cert is in essence signed by both intermediate certs at once.
I wonder if it would be possible to do the same thing on your own, actually: can a server present two completely separate cert chains to a connecting client - as long as the leaves use the same key pair? Technically AFAIK the only requirements should be 1) the key pair in use for the connection matches the cert, 2) the domain matches the cert's Subject, and 3) the cert is trusted, so at first glance it might be possible...
shame it wasn't adopted. rent seeking CAs would never go for it.
Another option: Use ACME together with ARI (RFC 9773). The client checks ARI data every hour. If the cert needs to be replaced – for example like in this scenario – the CA will inform the client, which in turn would then request a new cert.
I know it’s not convenient to automate for every kind of device though. I guess in some of those cases it might be better to have a load balancer in front of the device. Or use an alternative PKI.
I don't think that's the right way to think about it.
And then the browser could present these badges in a nice way to the user.
And then you have that one website trying to collect them all.
Certificates are not the same as the public key; multiple certs sharing the same key is essentially the way around this. It's not as elegant as identical signing of the same cert, but it could work.
And turning fields like issuer and serial into arrays risks someone accidentally using index 0 for one field and index 1 for another.
Combine that with the insane back-and-forth nightmare that the issuance process would turn into, and I have a very hard time seeing the benefit in it. After all, nobody is stopping you from requesting multiple certs independently, watching the revocation logs, and switching to the backup when required.
It's just an unfortunate unforced error that the go TLS package is bundled along with the compiler, in the same way Safari being bundled with iOS updates is an unforced error meaning a safari security bug requires a full OS update.
data from https://www.ccadb.org/resources
It's easy to imagine something like: "give us some grant taxpayers money and we'll add your cert to our trusted list/remove theirs cert/disable cert when run on this hardware/etc."
I wonder what's so annoying about OS certs.
[0]: https://www.rfc-editor.org/info/rfc5280/#section-4.2.1.10 [1]: https://utcc.utoronto.ca/~cks/space/blog/tech/TLSInternalCAN...