If the DNSSEC verifier (or whatever the correct term is) is inside the
application doing TLS - it isn't a problem.  (This *should* cover
browsers, when they get around to implementing DANE.)  It will
probably be handled in the same way Certificate Pinning is handled.
If a certificate is signed by a Root CA that is installed locally into
the trust store - Certificate Pinning does not apply.  Likewise, DANE
would (probably) not apply.

For any application that does not have a local trust store to install
root certificates in or does not perform it's own DNSSEC validation -
proxies would indeed break DANE.  And as mentioned, I think that is a
feature, not a problem.  If the application was willing to be proxied,
it would support those features as hook points to manipulation trust
validation.

-tom

On 12 October 2012 03:28, Marc Lampo <[email protected]> wrote:
> Before the draft was adopted as RFC I asked how to cope with proxies.
>
> On Sector 2012, last week, I was quite shocked to hear a speaker (also
> reading this, I assume) to simply state to get rid of them !
> I'd rather see continued work on how to make the principle of DANE
> apply/work even in the presence of proxies.
>
> The other security remark is that, in order for the browser to use
> info in TLSA record, the host needs access to public DNS.
>  (with the use of a proxy, a setup with internal-roots is possible,
> internal hosts don't need access to public IP addresses
>   if they use proxies)
> However, TLSA is not "an address", so access to public DNS is needed.
> But that (access to public DNS) allows for new threats in the area of
> data leakage !!!
>  One can do file transfer, both in and out of a network, using correct
> DNS messages, if access to public DNS is available.
>    (as I addressed, when still Security Officer for EURid, on CENTR
> Security WG meeting in June 2012, in Frankfurt)
>
> In summary :
>  Usage of TLSA, in its present form, opens new can of worms.
>  Which can only be kept closed if somehow collaboration of DANE (TLSA)
> and proxies can be achieved.
>
> Regarding DNSSEC :
> do not forget that adding signatures without verifying them is almost useless.
> And since *lots* of networks use AD, with its (non DNSSEC capable) DNS
> servers, only few users actually benefit, at this moment.
>  ("non DNSSEC capable" : since MS DNS does not support a protocol
> higher than 5, and treats everything higher as "unsigned":
>   + since the root zone uses protocol 8
>   --> this comes down to "not capable DNSSEC")
>
> So, wether or not the TLSA record is coming from a signed domain, most
> users are not capable of noticing this anyway.
>
> Kind regards,
>
> Marc Lampo
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