SuSE Linux Advisory: bind8
Nov 14, 2002, 14:22 (0 Talkback[s])
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SuSE Security Announcement
Date: Wed Nov 13 17:00:00 CET 2002
Affected products: (7.0), 7.1, 7.2, 7.3, 8.0, 8.1,
SuSE Linux Database Server
SuSE eMail Server III, 3.1
SuSE Linux Enterprise Server for S/390
SuSE Linux Connectivity Server
SuSE Linux Enterprise Server 7
SuSE Linux Office Server
Vulnerability Type: remote command execution
Severity (1-10): 8
SuSE default package: yes
Cross References: CVE CAN-2002-1219,
Content of this advisory:
1) security vulnerability resolved: Remote command execution
in bind8 name server.
problem description, discussion, solution and upgrade information
2) pending vulnerabilities, solutions, workarounds: BIND4, reports
of trojanized tcpdump/libpcap
3) standard appendix (further information)
1) problem description, brief discussion, solution, upgrade information
The security research company ISS (Internet Security Services)
has discovered several vulnerabilities in the BIND8 name server,
including a remotely exploitable buffer overflow.
Circumstancial evidence suggests that the Internet Software
Consortium (maintainer of BIND) has been made aware of these issues
in mid-October. Distributors of Open Source operating systems,
including SuSE, were notified of these vulnerabilities via CERT
approximately 12 hours before the release of the advisories by ISS
and ISC on Tue, Nov 12. This notification did not include any details
that allowed us to identify the vulnerable code, much less prepare
a fix. Mails to ISC went unanswered for 36 hours.
The SuSE security team regrets that the Internet Software Consortium
has withheld vital information from the Internet community for so long,
putting the majority of BIND users at risk. We would like to express
our concern that the approach chosen by ISC and ISS is likely to
erode trust in the security community if it becomes a model for dealing
with security issues.
We apologize to SuSE customers for not being able to provide timely
fixes for this problem.
The advisories by ISS and ISC mention the following problems
1. There is a buffer overflow in the way named handles
SIG records. This buffer overflow can be exploited to
obtain access to the victim host under the account
the named process is running with.
In order to exploit this problem, the attacker must
control an existing DNS domain, and must be allowed
to perform a recursive query.
The impact of this vulnerability is serious.
In all SuSE products, named is configured to run as user "named"
by default, so a potential attacker or virus/worm does not get
immediate root access. However, this is merely an additional
obstacle the attacker faces. It may be possible for the attacker
to exploit other, unpatched local vulnerabilities such as the
recently announced traceroute hole to obtain root privilege. It
may also be possible for an attacker to obtain increased privilege
by manipulating the DNS zones served by the victim BIND server.
We recommend to upgrade to the provided packages. If this is
not possible, we recommend to restrict recursive requests as a
workaround. This can be done by adding a statement such as the
following to /etc/named.conf:
... existing options ...
# Restrict recursive queries to 192.168.1.*,
# except 192.168.1.254.
# Order does matter.
Alternatively, you can add "recursion no;" to the options
section to turn off recursion completely.
2. There are several Denial Of Service problems in BIND8
that allow remote attackers to terminate the name server
At least one of these vulnerabilities seems to be exploitable
even when the attacker is not allowed to perform recursive
queries, so that the workaround suggested above is not
effective against this bug.
Both vulnerabilities are addressed by this update, using patches
originating from ISC.
Due to the severity of this issue, we will provide update packages
for SuSE Linux 7.0, even though support for this product has officially
Please download the update package for your distribution and verify its
integrity by the methods listed in section 3) of this announcement.
Then, install the packages using the command "rpm -Fhv file.rpm" to apply
the update. After updating, make sure to restart the name server
process by issuing the following command as root:
Our maintenance customers are being notified individually. The packages
are being offered to install from the maintenance web.
Intel i386 Platform:
AXP Alpha Platform:
PPC Power PC Platform:
2) Pending vulnerabilities in SuSE Distributions and Workarounds:
In addition to the vulnerabilities in BIND8 discussed above, ISS
report several vulnerabilities in BIND4. As stated previously,
SuSE has discontinued support for BIND4 and recommends that
users upgrade to BIND8 as soon as possible.
There have been reports that the source packages of tcpdump and
libpcap available from several FTP servers have been modified to
include a trojan. We have checked our source packages for this
and found them to be clean.
3) standard appendix: authenticity verification, additional information
- Package authenticity verification:
SuSE update packages are available on many mirror ftp servers all over
the world. While this service is being considered valuable and important
to the free and open source software community, many users wish to be
sure about the origin of the package and its content before installing
the package. There are two verification methods that can be used
independently from each other to prove the authenticity of a downloaded
file or rpm package:
1) md5sums as provided in the (cryptographically signed) announcement.
2) using the internal gpg signatures of the rpm package.
1) execute the command
after you downloaded the file from a SuSE ftp server or its mirrors.
Then, compare the resulting md5sum with the one that is listed in the
announcement. Since the announcement containing the checksums is
cryptographically signed (usually using the key firstname.lastname@example.org),
the checksums show proof of the authenticity of the package.
We disrecommend to subscribe to security lists which cause the
email message containing the announcement to be modified so that
the signature does not match after transport through the mailing
Downsides: You must be able to verify the authenticity of the
announcement in the first place. If RPM packages are being rebuilt
and a new version of a package is published on the ftp server, all
md5 sums for the files are useless.
2) rpm package signatures provide an easy way to verify the authenticity
of an rpm package. Use the command
rpm -v --checksig <file.rpm>
to verify the signature of the package, where <file.rpm> is the
filename of the rpm package that you have downloaded. Of course,
package authenticity verification can only target an un-installed rpm
a) gpg is installed
b) The package is signed using a certain key. The public part of this
key must be installed by the gpg program in the directory
~/.gnupg/ under the user's home directory who performs the
signature verification (usually root). You can import the key
that is used by SuSE in rpm packages for SuSE Linux by saving
this announcement to a file ("announcement.txt") and
running the command (do "su -" to be root):
gpg --batch; gpg < announcement.txt | gpg --import
SuSE Linux distributions version 7.1 and thereafter install the
key "email@example.com" upon installation or upgrade, provided that
the package gpg is installed. The file containing the public key
is placed at the top-level directory of the first CD (pubring.gpg)
and at ftp://ftp.suse.com/pub/suse/pubring.gpg-build.suse.de .
- SuSE runs two security mailing lists to which any interested party may
- general/linux/SuSE security discussion.
All SuSE security announcements are sent to this list.
To subscribe, send an email to
- SuSE's announce-only mailing list.
Only SuSE's security announcements are sent to this list.
To subscribe, send an email to
For general information or the frequently asked questions (faq)
send mail to:
SuSE's security contact is <firstname.lastname@example.org> or <email@example.com>.
The <firstname.lastname@example.org> public key is listed below.
The information in this advisory may be distributed or reproduced,
provided that the advisory is not modified in any way. In particular,
it is desired that the clear-text signature shows proof of the
authenticity of the text.
SuSE Linux AG makes no warranties of any kind whatsoever with respect
to the information contained in this security advisory.
Type Bits/KeyID Date User ID
pub 2048R/3D25D3D9 1999-03-06 SuSE Security Team <email@example.com>
pub 1024D/9C800ACA 2000-10-19 SuSE Package Signing Key <firstname.lastname@example.org>