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Home » Hacking News » SuSE Security Announcement: sendmail

SuSE Security Announcement: sendmail

by Nikola Strahija on March 3rd, 2003 A remotely exploitable buffer overflow has been found in all versions of sendmail that come with SuSE products. These versions include sendmail-8.11 and sendmail-8.12 releases. sendmail is the MTA subsystem that is installed by default on all SuSE products up to and including SuSE Linux 8.0 and the SuSE Linux Enterprise Server 7.

Package: sendmail, sendmail-tls
Announcement-ID: SuSE-SA:2003:013
Date: Monday, March 3rd 2003, 18:10 MET
Affected products: 7.1, 7.2, 7.3, 8.0, 8.1
SuSE Linux Database Server,
SuSE Linux Enterprise Server 7, 8
SuSE Linux Firewall on CD/Admin host
SuSE Linux Connectivity Server
SuSE Linux Office Server
Vulnerability Type: local privilege escalation
Severity (1-10): 7
SuSE default package: yes (until SuSE Linux 8.0 and SLES7)
Cross References:

Content of this advisory:
1) security vulnerability resolved: sendmail
problem description, discussion, solution and upgrade information
2) pending vulnerabilities, solutions, workarounds:
- vnc
- w3m
3) standard appendix (further information)


1) problem description, brief discussion, solution, upgrade information

sendmail is the most widely used mail transport agent (MTA) in the
internet. A remotely exploitable buffer overflow has been found in all
versions of sendmail that come with SuSE products. These versions include
sendmail-8.11 and sendmail-8.12 releases. sendmail is the MTA subsystem
that is installed by default on all SuSE products up to and including
SuSE Linux 8.0 and the SuSE Linux Enterprise Server 7.

The vulnerability is triggered by an email message sent through the
sendmail MTA subsystem. In that respect, it is different from commonly
known bugs that occur in the context of an open TCP connection. By
consequence, the vulnerability also exists if email messages get forwarded
over a relay that itself does not run a vulnerable MTA. This specific
detail and the wide distribution of sendmail in the internet causes this
vulnerability to be considered an error of major severity.

The buffer overflow happens on the heap and is known to be exploitable.
As of the writing of this announcement, there is no exploit known to exist
in the public. Since there is no known workaround for this vulnerability
other than using a different MTA, it is strongly recommended to install
the update packages as offered at the locations as listed below.

We would like to express our gratitude to Eric Allman for notifying
SuSE Security of the problem. The vulnerability was discovered by
ISS Internet Security Systems, inc.

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.

After performing the update, it is necessary to restart all running
instances of sendmail using the command "rcsendmail restart" as root.

Intel i386 Platform:

patch rpm(s):
source rpm(s):

patch rpm(s):
source rpm(s):

source rpm(s):

source rpm(s):

source rpm(s):

Sparc Platform:

source rpm(s):

AXP Alpha Platform:

source rpm(s):

PPC Power PC Platform:

source rpm(s):

source rpm(s):


2) Pending vulnerabilities in SuSE Distributions and Workarounds:

- vnc
VNC (Virtual Network Computing) uses a weak cookie generation process
which can be exploited by an attacker to bypass authentication.
New packages are currently being tested and will be available on our
FTP servers soon.

- w3m
The textbased web-browser w3m does not properly escape HTML tags.
A malicious HTML page or img alt attribute may lead to information
leakage. New packages will be available soon.

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 [email protected]),
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.

2) rpm package signatures provide an easy way to verify the authenticity
of an rpm package. Use the command
rpm -v --checksig
to verify the signature of the package, where 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.
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 protected]" 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 .

- SuSE runs two security mailing lists to which any interested party may

[email protected]
- general/linux/SuSE security discussion.
All SuSE security announcements are sent to this list.
To subscribe, send an email to

[email protected]
- 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 or .
The 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.

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