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Home » Hacking News » SuSE SA:2003:023: sendmail buffer overflow

SuSE SA:2003:023: sendmail buffer overflow

by Nikola Strahija on April 2nd, 2003 Buffer overflow vulnerability has been found in all versions of Sendmail earlier than 8.12.9, which may allow remote attackers to gain root privileges.


-----BEGIN PGP SIGNED MESSAGE-----

______________________________________________________________________________

SuSE Security Announcement

Package: sendmail, sendmail-tls
Announcement-ID: SuSE-SA:2003:023
Date: Tuesday, April 1st 2003 18:45 MEST
Affected products: 7.1, 7.2, 7.3, 8.0, 8.1, 8.2
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/remote privilege escalation
Severity (1-10): 7
SuSE default package: yes (until SuSE Linux 8.0 and SLES7)
Cross References: http://www.cert.org/advisories/CA-2003-12.html

Content of this advisory:
1) security vulnerability resolved: sendmail, sendmail-tls
problem description, discussion, solution and upgrade information
2) pending vulnerabilities, solutions, workarounds:
- glibc
- vnc
- openssl
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 was discovered by Michal Zalewski. It is not related
to the vulnerability found by ISS in the first week of March as announced
by SuSE Security in SuSE Security Announcement SuSE-SA:2003:013 (CERT
Announcement ID CA-2003-07). The impact is believed to be a local root
compromise with the possibility of a remote compromise. Even though
the remote nature of the vulnerability is not confirmed, we believe that
it is safe to assume that the vulnerability may be remotely exploitable.
The nature of the flaw is a stack overflow in a function that is called
frequently throughout the sendmail source code. The function is used for
processing email addresses.

There is no known workaround for this vulnerability other than using a
different MTA. 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 a flaw of major
severity. We recommend to install the update packages that are provided
for download at the locations listed below.

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.

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


Intel i386 Platform:

SuSE-8.1:
ftp://ftp.suse.com/pub/suse/i386/update/8.1/rpm/i586/sendmail-8.12.6-109.i586.rpm
bb987c277374db2cf5ec81b7abe9a476
patch rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.1/rpm/i586/sendmail-8.12.6-109.i586.patch.rpm
f90dc4e6f63b5c4e368e5db2fe7d09be
source rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.1/rpm/src/sendmail-8.12.6-109.src.rpm
dd838b1089f6686a1107e6d8159b1f98

SuSE-8.0:
ftp://ftp.suse.com/pub/suse/i386/update/8.0/n1/sendmail-8.12.3-75.i386.rpm
9e6949e973085ae3b628c52cadcc2c9e
patch rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.0/n1/sendmail-8.12.3-75.i386.patch.rpm
dac55a8afcb2487b8b80549b9a4d7b38
source rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.0/zq1/sendmail-8.12.3-75.src.rpm
f6e8297e885d367a73ff9010a6cbb297

SuSE-7.3:
ftp://ftp.suse.com/pub/suse/i386/update/7.3/n1/sendmail-8.11.6-164.i386.rpm
7591a1d397e161225b4d594bcfc5bb02
ftp://ftp.suse.com/pub/suse/i386/update/7.3/sec2/sendmail-tls-8.11.6-166.i386.rpm
52c213438e8782af09a4395d402d1fea
source rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/7.3/zq1/sendmail-8.11.6-164.src.rpm
a7b6f85673913089758f0ef0208aac6a
ftp://ftp.suse.com/pub/suse/i386/update/7.3/zq1/sendmail-tls-8.11.6-166.src.rpm
96cbfc4f2d85bdae71196ee80a4ebbd3

SuSE-7.2:
ftp://ftp.suse.com/pub/suse/i386/update/7.2/n1/sendmail-8.11.3-108.i386.rpm
b107d5a44b234222de7e5fcb7998c192
ftp://ftp.suse.com/pub/suse/i386/update/7.2/sec2/sendmail-tls-8.11.3-112.i386.rpm
78a987bd0a38d067a8cffd6c6003abd8
source rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/7.2/zq1/sendmail-8.11.3-108.src.rpm
0a86a2d3158110479c44c6b8a09f2bb6
ftp://ftp.suse.com/pub/suse/i386/update/7.2/zq1/sendmail-tls-8.11.3-112.src.rpm
acf234a4fa14d9d078df10cd774da0ce

SuSE-7.1:
ftp://ftp.suse.com/pub/suse/i386/update/7.1/n1/sendmail-8.11.2-45.i386.rpm
abec9a5d08d89cabc662708b38cadfad
ftp://ftp.suse.com/pub/suse/i386/update/7.1/sec2/sendmail-tls-8.11.2-47.i386.rpm
36ab02484b69d9f6ac9d58b78cc0569d
source rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/7.1/zq1/sendmail-8.11.2-45.src.rpm
e7e267fbb800277472f797f351796c6d
ftp://ftp.suse.com/pub/suse/i386/update/7.1/zq1/sendmail-tls-8.11.2-47.src.rpm
83b8fae134f192c53fa32c2d73f8dc8c



Sparc Platform:

SuSE-7.3:
ftp://ftp.suse.com/pub/suse/sparc/update/7.3/n1/sendmail-8.11.6-65.sparc.rpm
f3a9cff90e3ac9493bcab36b11dc692c
ftp://ftp.suse.com/pub/suse/sparc/update/7.3/sec2/sendmail-tls-8.11.6-65.sparc.rpm
63c14d646d8046df26c2899c0886bb24
source rpm(s):
ftp://ftp.suse.com/pub/suse/sparc/update/7.3/zq1/sendmail-8.11.6-65.src.rpm
7f01e6aa454231f35f6ee50958bb6f29
ftp://ftp.suse.com/pub/suse/sparc/update/7.3/zq1/sendmail-tls-8.11.6-65.src.rpm
e9086795f386471e6b2476febb419aa0




AXP Alpha Platform:

SuSE-7.1:
Limited package building resources are delaying the availiability of
update packages for the SuSE Linux 7.1 for Alpha distribution.


PPC Power PC Platform:

SuSE-7.3:
ftp://ftp.suse.com/pub/suse/ppc/update/7.3/n1/sendmail-8.11.6-123.ppc.rpm
1dd1154f1b9ede1dc003be26919b4d23
ftp://ftp.suse.com/pub/suse/ppc/update/7.3/sec2/sendmail-tls-8.11.6-122.ppc.rpm
a83a7f0885deb049a5a63d8114e47af4
source rpm(s):
ftp://ftp.suse.com/pub/suse/ppc/update/7.3/zq1/sendmail-8.11.6-123.src.rpm
2a199a60d825c8d3d2a1514fb58aea59
ftp://ftp.suse.com/pub/suse/ppc/update/7.3/zq1/sendmail-tls-8.11.6-122.src.rpm
621c390fbb8c44ffb1764d369c096d3f

SuSE-7.1:
ftp://ftp.suse.com/pub/suse/ppc/update/7.1/n1/sendmail-8.11.2-34.ppc.rpm
c1657f4dbc2f4967fb3ca04c17e2f1f3
ftp://ftp.suse.com/pub/suse/ppc/update/7.1/sec2/sendmail-tls-8.11.2-38.ppc.rpm
7f564cc83d85970cd7c0f61896c916e6
source rpm(s):
ftp://ftp.suse.com/pub/suse/ppc/update/7.1/zq1/sendmail-8.11.2-34.src.rpm
bd749453da2ff7513f09798d8b0b2e56
ftp://ftp.suse.com/pub/suse/ppc/update/7.1/zq1/sendmail-tls-8.11.2-38.src.rpm
1c347e9052b1b7dd02ae6630c56445db


______________________________________________________________________________

2) Pending vulnerabilities in SuSE Distributions and Workarounds:

- glibc
SuSE Security is working on glibc updates for the RPC XDR integer overflow
security problem in glibc. The central function of the glibc package in a
Linux system requires extensive testing of the update packages. The update
packages will be provided for download at the usual location and
publically announced as soon as the testing is completed successfully.

- 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.

- openssl
A paper regarding remote timing attacks against OpenSSL has been
published by researchers of the Stanford University. It is possible
to extract the private RSA key used by services using OpenSSL by
observing their timing behavior. Fixed packages will be available
on our FTP servers 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
md5sum
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.
Prerequisites:
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 ftp://ftp.suse.com/pub/suse/pubring.gpg-build.suse.de .


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

[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:
or
respectively.

=====================================================================
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.

Type Bits/KeyID Date User ID
pub 2048R/3D25D3D9 1999-03-06 SuSE Security Team
pub 1024D/9C800ACA 2000-10-19 SuSE Package Signing Key

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Roman Drahtmüller,
SuSE Security.
- --
- -
| Roman Drahtmüller // "You don't need eyes to see, |
SuSE Linux AG - Security Phone: // you need vision!"
| Nürnberg, Germany +49-911-740530 // Maxi Jazz, Faithless |
- -

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