[dns-operations] summary of recent vulnerabilities in DNS security.

P Vixie vixie at fsi.io
Mon Oct 21 10:42:08 UTC 2013

On Tuesday, October 22, 2013 19:47:34 Haya Shulman wrote:
> On Tue, Oct 22, 2013 at 6:20 PM, Paul Vixie <paul at redbarn.org> wrote:
> > note, i am using <http://arxiv.org/pdf/1205.4011.pdf> as my reference to
> > haya shulman's fragmentation related attack. i found this by googling for
> > "fragmentation considered poisonous" which is the string i used to
> > reference haya's work in my circleid blog post.
> updated papers are available.
> sites.google.com/site/hayashulman/publications

so noted.

> > so if i add "first weaponized by Haya Shulman" this would settle the
> > matter?
> Thank you, can you please use Amir Herzberg and Haya Shulman (I
> collaborated on this attack together with my phd advisor Amir Herzberg).

it shall be done.

> I agree with you that there are other vulnerabilities, which may be easier
> for attackers to exploit, that have to be addressed.

do you also agree with me that they would have to be addressed first, since 
they represent greater risks, and do you also agree that if the other known 
problems are addressed (for example, using eastlake cookies) that your 
fragmentation related vulnerabilities will have been resolved by side-effect?

> > ... not all experts think that outsourcing
> > recursive dns (to opendns, or to google, or to one's ISP) is secure or
> > reasonable. i want the record to be clear on that point -- people should
> > run their own recursive dns, on-prem or in-laptop. i'll make an exception
> > for smart phones, who should be using their provider's recursive DNS, and
> > not google's or opendns. your observations about fragmentation related
> > vulnerabilities in the use of wide area recursive dns are welcome, since
> > we need more nails for the coffin that wide area recursive dns belongs in.
> > but it was already a bad idea even before your fragmentation related
> > observations were published.
> I absolutely agree with you, deploying DNSSEC on the end hosts would be
> ideal for security.

wait, wait, that's not what i said. i said recursive dns should be on-premise 
or on-host, not wide-area. i said nothing about end to end dnssec. what are 
you specifically agreeing with?

> There are obstacles to this though, that may have to be addressed in some
> networks, including support by applications, interoperability problems, and
> even other issues that may discourage clients from validating, e.g., as you
> published, ISPs mangling NXDOMAIN responses.

this is nonsequitur. it's as if i'd asserted A and you'd said "B is 

> I think I may have been misinterpreted. I believe cryptography is important
> and efforts should be invested in deployment of DNSSEC. One of the goals of
> our work on DNS was to motivate adoption of DNSSEC.

that's great to hear.


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