full-disclosure - Re: bind dos info?

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Date: Wed, 16 Nov 2011 21:06:42 -0500
From: Michael Wood <itnetsec@...il.com>
To: "Larry W. Cashdollar" <bugs@....dhs.org>
Cc: full-disclosure@...ts.grok.org.uk
Subject: Re: bind dos info?

Nope...I haven't seen anything yet either.  Maybe someone else can
enlighten us? ;)
On Nov 16, 2011 9:05 PM, "Larry W. Cashdollar" <bugs@....dhs.org> wrote:

> Thanks Michael!
>  I guess 'ISC is working on determining the ultimate cause by which a
> record with this particular inconsistency is cached' is the part I'm
> interested in reading about and there are no details yet..
>
> > http://www.isc.org/software/bind/advisories/cve-2011-4313
> > On Nov 16, 2011 8:53 PM, "Larry W. Cashdollar" <bugs@....dhs.org> wrote:
> >
> >> Hello list,
> >> I am wondering if anyone has more details on the bind9 DoS that just
> >> came
> >> out? (CVE-2011-4313) from what I can tell it appears a negative cached
> >> DNS
> >> object with a valid RR response associated with it(which shouldn't
> >> exist)
> >> will cause a vulnerabile bind9 server to crash.
> >>
> >> See lines 1890 - 1896 of query.c
> >> 1890         if (result == DNS_R_NCACHENXRRSET) {
> >> 1891                 dns_rdataset_disassociate(rdataset);
> >> 1892                 /*
> >> 1893                  * Negative cache entries don't have sigrdatasets.
> >> 1894                  */
> >> 1895                 INSIST(! dns_rdataset_isassociated(sigrdataset));
> >> 1896         }
> >>
> >>
> >> Since allowing recursive queries must be enabled for this to work the
> >> attacker  must force a vulnerable dns server to query a malicous DNS
> >> server by asking it to look up an NXrecord for a domain the attacker
> >> controls dns for.  Sending a response of NXdomain but having actual DNS
> >> results in the response.
> >>
> >> I am wondering if someone has seen a good write up out there?
> >>
> >> Thanks
> >> -- Larry C$
> >>
> >>
> >> _______________________________________________
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> >>
> >
>
>
>

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Full-Disclosure - We believe in it.
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