[Discuss] free SSL certs from the EFF

[warlord at MIT.EDU (Derek Atkins)]

Richard,

Richard Pieri <richard.pieri at gmail.com> writes:

> Derek,
>
> According to the DNSSEC specs, if there is no RRSIG record in the
> lookup answer then a properly behaved resolver will treat it as
> unsigned. Backwards compatibility with so-called insecure DNS is an
> explicit requirement of DNSSEC. So, what happens when a malicious
> actor inserts filters at an intermediary resolver or router that strip
> RRSIG records from DNS answers?

Which RFC states this?  I'm quite familiar with 4033 et al, (and even
moreso with their predecessors, 2535 et al).  Granted, I did stop
following the specs somewhere around the NSEC3 discussions, but it was
certainly the case that a DNSSEC-aware resolver would always know
whether to expect signed data.  I.e., if there is no DS record for the
zone then a DNSSEC-aware resolver knows it's not a signed zone.  If
there IS a DS record for the zone and then a query does not return an
RRSIG or NSEC then there's a problem (verification failure).

Obviously a non-DNSSEC-aware resolver doesn't care.

> DNSSEC was never intended to protect you against that. It was designed
> to protect high-level caches -- root zones, ISP's, big data players,
> private networks, and the like -- from cache poisoning. That's it. Any
> benefits that might trickle down to you are incidental.

Actually, it was designed to protect against that.  I sat in the
IETF meetings where that was explicitly discussed.  If an intermediary
strips the DNSSEC records out then a resolver expecting DNSSEC will
force a validation error.

> Never mind that DNSSEC has no means of rolling over the root KSKs. If
> a root is compromised then the whole domain hierarchy is compromised
> and there currently is no way to fix that other than disabling DNSSEC
> for the hierarchy or accepting loss of service for everything under
> that root.

Well, it sort of does, but it's not easy.  But this is why they use
ZSKs.  The Root Zone KSK is mightily protected.

-derek

-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
       warlord at MIT.EDU                        PGP key available