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AUSCERT External Security Bulletin Redistribution
ESB-2007.0440 -- [Solaris]
Security Vulnerability in Solaris 10 BIND DNSSEC May Cause a
Denial of Service
20 June 2007
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AusCERT Security Bulletin Summary
---------------------------------
Product: named
Publisher: Sun Microsystems
Operating System: Solaris 10
Impact: Denial of Service
Access: Remote/Unauthenticated
CVE Names: CVE-2007-0494
Ref: ESB-2007.0050
Original Bulletin:
http://sunsolve.sun.com/search/printfriendly.do?assetkey=1-26-102969-1
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Sun(sm) Alert Notification
* Sun Alert ID: 102969
* Synopsis: Security Vulnerability in Solaris 10 BIND DNSSEC May
Cause a Denial of Service
* Category: Security
* Product: Solaris 10 Operating System
* BugIDs: 6532492
* Avoidance: Patch
* State: Resolved
* Date Released: 18-Jun-2007
* Date Closed: 18-Jun-2007
* Date Modified:
1. Impact
A security vulnerability in Solaris 10 BIND DNSSEC may allow a local
or remote unprivileged user the ability to cause the "named" BIND
server process to exit (see also named(1M)). A Denial of Service (DoS)
occurs as clients are unable to resolve addresses from or make dynamic
updates to the server.
This issue is also referenced in the following document:
CVE-2007-0494 at:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-0494
2. Contributing Factors
This issue can occur in the following releases:
SPARC Platform
* Solaris 10 without patch 119783-02
x86 Platform
* Solaris 10 without patch 119784-02
Notes:
1. Solaris 8 and Solaris 9 are not impacted by this issue.
2. Systems are only impacted by this issue if the BIND named(1M)
service is configured for DNSSEC and is enabled.
To determine if DNSSEC is configured and enabled on a system, search
for 'dnssec-enable yes' in the BIND configuration file
"/etc/named.conf" by running the following command:
$ grep -i dnssec-enable /etc/named.conf
dnssec-enable yes;
To verify if the DNS service instance is enabled under SMF(5), use the
svcs(1M) command as follows:
$ svcs -l svc:/network/dns/server:default | grep enabled
enabled true
3. Symptoms
Should the described issue occur, the BIND server will not respond to
client resolver(3RESOLV) requests. The "named" process may no longer
be running, or it may be seen to be restarted erratically by the
SMF(5) service.
In the following example, dig(1) is unable to contact the DNS server
as listed in "/etc/resolv.conf," while the DNS server is still found
to be otherwise alive:
$ dig example.sun.com
; <<>> DiG 9.2.4 <<>> @192.168.0.1 example.sun.com
; (1 server found)
;; global options: printcmd
;; connection timed out; no servers could be reached
On the DNS server, the state of the managed SMF instance may be
checked by running svcs(1) command. For a full list of possible
states, refer to the SMF(5) manual page. The following is an example
depicting an online state:
$ svcs svc:/network/dns/server:default
STATE STIME FMRI
online 16:24:04 svc:/network/dns/server:default
If the Start Time (STIME) is not as expected, it may be that SMF(5) is
automatically restarting named(1M) after the DoS was attempted.
If the STATE is 'maintenance', then the service instance failed to
start or remain running. Examine the instance log file for further
details using the following command:
$ tail -100 `svcprop -p restarter/logfile svc:/network/dns/server:default`
4. Relief/Workaround
To work around this issue until patches can be applied, disable DNSSEC
functionality by setting 'dnssec-enable' to "no" in /etc/named.conf.
Note this may affect the security of DNS transactions as the
facilities provided by DNSSEC will no longer be available.
Once the configuration file has been altered, the DNS service must be
restarted by running the svcadm(1) command as follows:
# svcadm -v enable svc:/network/dns/server:default
svc:/network/dns/server:default enabled
followed by:
# svcadm -v restart svc:/network/dns/server:default
Action restart set for svc:/network/dns/server:default
5. Resolution
This issue is addressed in the following releases:
SPARC Platform
* Solaris 10 with patch 119783-02 or later
x86 Platform
* Solaris 10 with patch 119784-02 or later
The resolution above provides BIND 9.3.4 which implements DNSSEC-bis.
After the patch has been installed, it is recommended that BIND
administrators familiarize themselves with
"/usr/share/doc/bind/migration.txt"
More information on BIND 9.3 and DNSSEC-bis is available in the "BIND
9.3 Advanced Reference Manual" (ARM), available on the ISC web site at
http://www.isc.org/sw/bind/arm93/index.php.
This Sun Alert notification is being provided to you on an "AS IS"
basis. This Sun Alert notification may contain information provided by
third parties. The issues described in this Sun Alert notification may
or may not impact your system(s). Sun makes no representations,
warranties, or guarantees as to the information contained herein. ANY
AND ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION
WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR
NON-INFRINGEMENT, ARE HEREBY DISCLAIMED. BY ACCESSING THIS DOCUMENT
YOU ACKNOWLEDGE THAT SUN SHALL IN NO EVENT BE LIABLE FOR ANY DIRECT,
INDIRECT, INCIDENTAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES THAT ARISE
OUT OF YOUR USE OR FAILURE TO USE THE INFORMATION CONTAINED HEREIN.
This Sun Alert notification contains Sun proprietary and confidential
information. It is being provided to you pursuant to the provisions of
your agreement to purchase services from Sun, or, if you do not have
such an agreement, the Sun.com Terms of Use. This Sun Alert
notification may only be used for the purposes contemplated by these
agreements.
Copyright 2000-2006 Sun Microsystems, Inc., 4150 Network Circle, Santa
Clara, CA 95054 U.S.A. All rights reserved
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