SuSE Linux Advisory: sendmail
Aug 26, 2003, 23:29 (0 Talkback[s])
SuSE Security Announcement
||Tuesday, Aug 26th 2003 19:00 MEST
||8.0, 8.1, 8.2
SuSE Linux Enterprise Server 8
|SuSE default package:
Content of this advisory:
- security vulnerability resolved: calling free() with arbitrary
argument problem description, discussion, solution and upgrade
- pending vulnerabilities, solutions, workarounds:
- standard appendix (further information)
1) problem description, brief discussion, solution, upgrade
The well known and widely used MTA sendmail is vulnerable to a
remote denial-of-service attack in version 8.12.8 and earlier (but
not before 8.12). The bug exists in the DNS map code. This feature
is enabled by specifying FEATURE(`enhdnsbl'). When sendmail
receives an invalid DNS response it tries to call free(3) on random
data which results in a process crash.
After your system was updated you have to restart your sendmail
daemon to make the update effective.
There is no known workaround for this vulnerability other than
using a different MTA.
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 package using the command "rpm -Fhv
file.rpm" to apply the update.
Our maintenance customers are being notified individually. The
packages are being offered to install from the maintenance web.
Intel i386 Platform:
Intel i386 Platform:
2) Pending vulnerabilities in SuSE Distributions and
- traceroute(-nanog) A integer overflow in traceroute can be
abused by local attackers to gain access to a raw IP socket. New
packages are available on out FTP servers.
- gdm2 Due to a bug in GDM it is possible for local users to read
any text file on a system by creating a symlink from
~/.xsession-errors. Updated packages will be available on our FTP
- pam_smb A buffer overflow in the password handling function of
pam_smb allows remote root compromise. Fixed packages will be
- exim Two bugs where fixed in exim. One bug allows remote access
as user mail/mail and the other one allows local root access for
'Admin Users'. Fixed packages are available on our FTP
3) standard appendix: authenticity verification, additional
- 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:
- md5sums as provided in the (cryptographically signed)
- using the internal gpg signatures of the rpm package.
- execute the command md5sum <name-of-the-file.rpm> 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 list software.
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.
- 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 package file. Prerequisites:
- gpg is installed
- 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 subscribe:
For general information or the frequently asked questions (faq)
send mail to:
SuSE's security contact is <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.
||SuSE Security Team <email@example.com>
||SuSE Package Signing Key <firstname.lastname@example.org>
Thomas Biege <email@example.com>