3 ms·

It doesn't seem to actually require DNSSEC. Let's Encrypt will happily use these new fields to restrict issuance, the same way they were checking CAA records pr

by akerl_ 4y ago

It doesn't seem to actually require DNSSEC. Let's Encrypt will happily use these new fields to restrict issuance, the same way they were checking CAA records previously, for domains with and without DNSSEC.

dinosaurdynasty 4y ago
It requires DNSSEC to prevent MITM between the CA and the domain's nameservers.
- regecks 4y ago
  In this context, I think "requires DNSSEC" is an opinion at best. "Requires" is probably the wrong word. You are welcome to use CAA accounturi without DNSSEC and it will be effective. Your zone may be vulnerable to an active man-in-the-middle DNS attack (which is hard to pull off), but it will still be protected against somebody figuring out how to upload an /.well-known/acme-challenge/ file on your domain and issue an unauthorized certificate from a foreign ACME account. This attack is much easier - I did it against a popular mail provider a few years ago.
  - zinekeller 4y ago
    > This attack is much easier - I did it against a popular mail provider a few years ago. I guess this is Fastmail :)
    - holigot 4y ago
      Can't even understand, why they do not give us some features like IPv6, DANE, DNSSEC and so on... https://fastmail.blog/historical/fastmail-dns-hosting/ https://fastmail.blog/historical/fastmail-dns-hosting/ In 2014 Rob Mueller wrote: "Our future DNS plans include DNSSEC support (which then means we can also do DANE properly, which allows server-to-server email sending to be more secure), DMARC record support, and ideally one day Anycast support to make DNS lookups faster."
rocqua 4y ago
Without DNSSEC this requires an attacker to 'global MITM' letsencrypt's DNS queries. That is a higher bar than before this change. Before, an attacker only needed to 'global MITM' http requests. Your ISP could trivially do that. But your ISP couldn't just global MitM DNS queries for your domain unless you happen to use them as your registrar. That is much harder than having an attacker use HTTP verification and global MITM the end user.

by akerl_ 4y ago

dinosaurdynasty 4y ago

It requires DNSSEC to prevent MITM between the CA and the domain's nameservers.

regecks 4y ago
In this context, I think "requires DNSSEC" is an opinion at best. "Requires" is probably the wrong word. You are welcome to use CAA accounturi without DNSSEC and it will be effective. Your zone may be vulnerable to an active man-in-the-middle DNS attack (which is hard to pull off), but it will still be protected against somebody figuring out how to upload an /.well-known/acme-challenge/ file on your domain and issue an unauthorized certificate from a foreign ACME account. This attack is much easier - I did it against a popular mail provider a few years ago.
- zinekeller 4y ago
  > This attack is much easier - I did it against a popular mail provider a few years ago. I guess this is Fastmail :)
  - holigot 4y ago
    Can't even understand, why they do not give us some features like IPv6, DANE, DNSSEC and so on... https://fastmail.blog/historical/fastmail-dns-hosting/ https://fastmail.blog/historical/fastmail-dns-hosting/ In 2014 Rob Mueller wrote: "Our future DNS plans include DNSSEC support (which then means we can also do DANE properly, which allows server-to-server email sending to be more secure), DMARC record support, and ideally one day Anycast support to make DNS lookups faster."

rocqua 4y ago

Without DNSSEC this requires an attacker to 'global MITM' letsencrypt's DNS queries. That is a higher bar than before this change. Before, an attacker only needed to 'global MITM' http requests. Your ISP could trivially do that. But your ISP couldn't just global MitM DNS queries for your domain unless you happen to use them as your registrar. That is much harder than having an attacker use HTTP verification and global MITM the end user.