[AusNOG] DNS Cache Poisoning Vulnerability

[Noel Butler]

On Fri, 2008-08-08 at 08:39, Bob Purdon wrote: 

> I'll get the guys to check -  they assured me our DNS servers were
> upgraded a few weeks back, so this is a little strange...


Brent is correct...

# dig +short porttest.dns-oarc.net TXT @ns1.pipenetworks.com
porttest.y.x.w.v.u.t.s.r.q.p.o.n.m.l.k.j.i.h.g.f.e.d.c.b.a.pt.dns-oarc.net.
"203.161.158.2 is POOR: 26 queries in 4.5 seconds from 1 ports with std
dev 0"

# dig +short porttest.dns-oarc.net 
TXT at ns2.pipenetworks.com.                                                                              
porttest.y.x.w.v.u.t.s.r.q.p.o.n.m.l.k.j.i.h.g.f.e.d.c.b.a.pt.dns-oarc.net.
"203.161.158.3 is POOR: 26 queries in 4.6 seconds from 1 ports with std
dev 0"


It is possible they have made the mistake of leaving a source-port
directive in named.conf





> Bob Purdon
> General Manager,
> Managed Infrastructure,
> PIPE Networks Limited (ASX:pwk)
> 
> Phone  : +61 7 3233 9844
> Fax    : +61 7 3233 9885
> Web    : www.pipenetworks.com
> 
> Any information transmitted in this message and its attachments is
> intended only for the person or entity to which it is addressed. The
> above email correspondence should be read in conjunction with our
> standard disclaimer/terms which can be found at
> www.pipenetworks.com/docs/disclaimer.htm
> 
> ----- Original Message -----
> From: ausnog-bounces at lists.ausnog.net
> <ausnog-bounces at lists.ausnog.net>
> To: ausnog at ausnog.net <ausnog at ausnog.net>
> Sent: Fri Aug 08 08:05:06 2008
> Subject: Re: [AusNOG] DNS Cache Poisoning Vulnerability
> 
> That is quite a handy and easy to use tool.  ausnog.net's nameservers
> need patching though by
> the looks :
> 
> "Highly vulnerable.
> 
> The servers tested for AUSNOG.NET are highly vulnerable to cache
> poisoning. Immediate action should be taken to rectify the problem."
> 
> I'm sure someone on this list will be able to rectify that.
> 
> Brent
> 
> Brent Paddon
> 
> Director | Over the Wire Pty Ltd
> brent.paddon at overthewire.com.au | www.overthewire.com.au
> Phone: 07 3847 9292 | Fax: 07 3847 9696 | Mobile: 0400 2400 54 |
> Direct: 07 3503 4807
> 
> 
> 
> Kim Davies wrote:
> > Hi folks,
> >
> > A number of you have likely heard about this already, but just in
> case
> > not, this is a fairly serious issue that deserves a few minutes of
> > attention.
> >
> > Recently, it was discovered that the amount of entropy in DNS
> queries is
> > relatively low in typical DNS software implementations, making the
> > ability to spoof answers a fairly trivial exercise that can take as
> > little as a second. This can be used to poison DNS caches, and
> > ultimately introduce false data into the DNS.
> >
> > This is important on two distinctly different fronts:
> >
> > 1) Recursive name servers should have the maximum amount of entropy
> >    to provide the strongest resistance to spoofed DNS responses.
> This won't
> >    solve the problem, but helps mitigate the risk. There are
> >    patches for BIND etc. now available to randomise the source port
> of
> >    queries to aid this. To test a recursive name server you can use
> >    the tool at
> >
> >    https://www.dns-oarc.net/oarc/services/dnsentropy
> >
> > 2) For domain registrants, the authoritative name server for your
> >    domain can be affected if they also offer recursive name service.
> >    The effects of cache poisoning can therefore introduce false
> >    data into your zone. To test for vulnerable servers, there is a
> >    new tool at
> >
> >    http://recursive.iana.org/
> >
> >    The solution to this problem is to separate recursive and
> >    authoritative name service from one another.
> >
> > There is also an FAQ, focused on part 2, at
> > http://www.iana.org/reports/2008/cross-pollination-faq.html
> >
> > cheers,
> >
> > kim
> > _______________________________________________
> > AusNOG mailing list
> > AusNOG at lists.ausnog.net
> > http://lists.ausnog.net/mailman/listinfo/ausnog
> >  
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> 
> 
> 
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> 
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--

Kind Regards,

Noel Butler

Network Administrator

L.C.P # 251002 

(http://counter.li.org)



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