Subject: [dnsop] An attack that DNSSEC would have defended against...

From: Harald Tveit Alvestrand <[email-masked]>
Date: Fri, 23 Sep 2005 08:44:44 +0200

I'm not sure this is on-topic for this list, but may be an illustrative 
story....

I had some percentage of the queries for a domain I use hijacked by an 
attacker last week. The technique involved was interesting to me.

Moral: Know your secondaries, and what happens to them..... if someone 
steals your secondary's NAME, you're toast.

If I'd had DNSSEC, and the people looking it up had had DNSSEC, this would 
have been a detectable DOS attack, not a stealth redirection attack.

Detailed writeup: http://www.alvestrand.no/subjects/dns-attack-1.html

                      Harald

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dnsop resources:_____________________________________________________
web user interface: http://darkwing.uoregon.edu/~llynch/dnsop.html
mhonarc archive: http://darkwing.uoregon.edu/~llynch/dnsop/index.html

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From: Stephane Bortzmeyer <[email-masked]>
Date: Fri, 23 Sep 2005 11:51:53 +0200

On Fri, Sep 23, 2005 at 08:44:44AM +0200,
 Harald Tveit Alvestrand <[email-masked]> wrote 
 a message of 21 lines which said:

> If I'd had DNSSEC, and the people looking it up had had DNSSEC, 

*And* if they knew that the zone should be signed (most zones will
not, during the transition and no DS would be there to tell it).

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From: Harald Tveit Alvestrand <[email-masked]>
Date: Fri, 23 Sep 2005 12:16:09 +0200

> not, during the transition and no DS would be there to tell it).

I don't consider that I "have" DNSSEC until I have a chain of signatures 
from a commonly known public key..... probably the root, but .org might be 
Good Enough for this particular instance..... until then, I consider 
everything I do "just experimenting".

YMMV.

.

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From: Dean Anderson <[email-masked]>
Date: Fri, 23 Sep 2005 18:09:23 -0400 (EDT)

Harald, you may be right about DNSSEC protecting from this. I haven't looked at
your data, yet. However, you probably aren't about to be very well protected by
DNSSEC, despite the progress of specifications on DNSEXT.

DNSSEC isn't deployable on F-root nor the other anycast'ed* roots, nor a lot of
other anycast'ed non-root servers.  DNS servers with the Anycast Extension are
increasingly popular due to suppression of discussion of negative aspects of the
Anycast Extension on forums such as Nanog as recently as May, 2005 because only
information that promotes ISC's view is allowed on Nanog, misleading network
operators about the Anycast Extension.  Many root server operators accepted
ISC's assurances as an unofficial IETF liason and deployed Anycast Extension on
production servers and on root servers in violation of RFC 2870**. They appear
not to have understood that they were deploying an untested, undocumented, and
unapproved Anycast Extension.

And despite substantiated criticism on DNSEXT and DNSOP by persons including Dan
Bernstein, Iljitsch van Beijnum, Dean Anderson, and others since the 2002 Nanog
presentation by ISC, ISC has not yet even publicly acknowledged the problems
with the Anycast Extension, and continues to promote the extension as completely
safe. ISC even describes it to prospective customers as "uncontroversial",
despite the controversies on DNSEXT, DNSOP, and Nanog beginning after the Nanog
presentation in 2002.  

The Anycast Extension is now proposed to the GROW working group some 3 years
after being described to Nanog as operationally safe and stable.  At present,
the Anycast Extension proposal appears to be dead or dying on both DNSOP and
GROW WGs because of evidence that it can't work in general, and the specialized
conditions where it can work are uninteresting to the current users such as root
DNS operators and other DNS operators, and thus uninteresting to ISC.

The only reason there are no present complaints with root operations is that DNS
is mostly still stateless small UDP packets, reducing to RFC 1546 Anycast***,
which works fine with stateless small UDP packets. And it may well be that those
working on DNSSEC testing comply with the assumptions stated on the Anycast
Extension.

So the question is when will F-root and other roots be able to handle TCP and
large UDP packets from any internet host, including those hosts serviced by
networks that use fine-grained load-splitting as described by RFC1812?.  When
will operators be informed of these problems by ISC?

Critics of these problems, particularly Dan Bernstein and Dean Anderson, have
been attacked personally by persons generally associated with ISC or friendly to
ISC with no remedial action by the respective organizations (IETF and Nanog) in
spite of well-documented complaints.  Uncontrolled personal corruption at the
IETF and Nanog appears to be preventing actual progress.

                --Dean

[* the Anycast Extension
http://www.ietf.org/internet-drafts/draft-ietf-grow-anycast-01.txt doesn't work
in general because routers are allowed by RFC1812 to do fine-grained "load
splitting" if they wish. Fine-grained load splitting, also known as Per Packet
Load Balancing (PPLB) and other names, prevents Anycast from being used with TCP
or large UDP packets and fragments. The draft documents a number of assumptions
that have to be true in order for the Anycast Extension to work. These
assumptions aren't true in general.]

[** RFC 2870 section 2.6 specifies that Root DNS server operators must operate
servers that respond to _any_ Internet host.  That is, Root nameservers that
only work for say, 95% of the world are not acceptable.

   2.6 Root servers MUST answer queries from any internet host, i.e. may
       not block root name resolution from any valid IP address, except
       in the case of queries causing operational problems, in which
       case the blocking SHOULD last only as long as the problem, and be
       as specific as reasonably possible.
]

[*** RFC1546 notes that:

   It is important to remember that anycasting is a stateless service.
   An internetwork has no obligation to deliver two successive packets
   sent to the same anycast address to the same host.
]

-- 
Av8 Internet   Prepared to pay a premium for better service?
www.av8.net         faster, more reliable, better service
617 344 9000   

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From: David Kessens <[email-masked]>
Date: Fri, 23 Sep 2005 15:36:11 -0700

Dean,

You are welcome to post to this list if you have DNS operational
issues to discuss.

Any issues that you might have with ISC are outside the charter of
this working group and I would like to request you to take them up
privately with ISC. 

Thanks,

David Kessens
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> > mhonarc archive: http://darkwing.uoregon.edu/~llynch/dnsop/index.html

David Kessens
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From: Dean Anderson <[email-masked]>
Date: Fri, 23 Sep 2005 20:06:00 -0400 (EDT)

ISC's mis-operation of root DNS services and the impact of that mis-operation is
plainly a genuine DNS operational issue.

		--Dean

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From: David Conrad <[email-masked]>
Date: Fri, 23 Sep 2005 17:33:44 -0700

Dean,

Could you point to the data (not the theory) by which you have  
determined ISC is mis-operating F and the impact of that mis-operation?

Thanks,
-drc

On Sep 23, 2005, at 5:06 PM, Dean Anderson wrote:

>>>> this would
>>>> dnsop  
>>>> resources:_____________________________________________________
>>> dnsop  
>>> resources:_____________________________________________________

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From: Dean Anderson <[email-masked]>
Date: Fri, 23 Sep 2005 21:38:07 -0400 (EDT)

Test (ie lab) data has been obtained to show that most Cisco routers (ie
non-GSR)  can perform fine grained load balancing.  Cisco manuals indicate that
the GSR series routers do fine grained load balancing.

Test (ie lab) data has been obtained to demonstrate that the Anycast Extension
(TCP) does not work in theory or in practice with fine grained, per packet load
balancing.

Root DNS specific operational data will be obtained when more people start
making TCP and large UDP packets and fragments to root servers.  There is no
reason (in theory or in practice) to expect that the Anycast Extension can work
in general, or that current lab results won't be experienced.

However, all of the questions about the operational impact of the Anycast
Extension should have been __TESTED__ BEFORE deployment on critical servers such
as root servers.  Even if the Anycast Extension worked, ISC would be still be
subject to valid and substantial criticism for deploying it on Root servers
without adequate testing and analysis, and IETF review.

That the Anycast Extension doesn't work in general only adds to the criticism
and the seriousness of the problem.

		--Dean

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