full-disclosure - bind dos info?

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <68bb5fb170cd8eab82590662888d090c.squirrel@fbi.dhs.org>
Date: Thu, 17 Nov 2011 11:51:09 -0500 (EST)
From: "Larry W. Cashdollar" <bugs@....dhs.org>
To: full-disclosure@...ts.grok.org.uk
Subject: bind dos info?

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$

_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/