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SuSE Linux Advisory: sendmail

Aug 26, 2003, 23:29 (0 Talkback[s])

SuSE Security Announcement

Package: sendmail
Announcement-ID: SuSE-SA:2003:035
Date: Tuesday, Aug 26th 2003 19:00 MEST
Affected products: 8.0, 8.1, 8.2
SuSE Linux Enterprise Server 8
remote denial-of-service
Severity (1-10): 5
SuSE default package: no
Cross References: CAN-2003-0688

Content of this advisory:

  1. security vulnerability resolved: calling free() with arbitrary

    argument problem description, discussion, solution and upgrade information

  2. pending vulnerabilities, solutions, workarounds:
    • traceroute(-nanog)
    • gdm2
    • pam_smb
    • exim
  3. standard appendix (further information)

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

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:

SuSE-8.2:
ftp://ftp.suse.com/pub/suse/i386/update/8.2/rpm/i586/sendmail-8.12.7-73.i586.rpm eaf90e49886f496b2779107f1d9a831a
patch rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.2/rpm/i586/sendmail-8.12.7-73.i586.patch.rpm c5999fe4026e05c4308249a7e3dbf8f4
source rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.2/rpm/src/sendmail-8.12.7-73.src.rpm 2cda6c535a3be4e26c50373bd078b4c7

SuSE-8.1:
ftp://ftp.suse.com/pub/suse/i386/update/8.1/rpm/i586/sendmail-8.12.6-147.i586.rpm 03d2b6e1083f863dc19a28f44256b071
patch rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.1/rpm/i586/sendmail-8.12.6-147.i586.patch.rpm ee6a3553396432bd3a208d355dacdd33
source rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.1/rpm/src/sendmail-8.12.6-147.src.rpm 97417cee623251c6cc3009c13c5b1fbe

SuSE-8.0:
ftp://ftp.suse.com/pub/suse/i386/update/8.0/n1/sendmail-8.12.3-76.i386.rpm c7cd791bdbcf0c5ed80cd9aab0ccc965
patch rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.0/n1/sendmail-8.12.3-76.i386.patch.rpm a2d04f73894a09b9134f0f516c385d78
source rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.0/zq1/sendmail-8.12.3-76.src.rpm 4c059b5714ba2dbe5860654622b65bfb

Intel i386 Platform:

SuSE-8.2:
ftp://ftp.suse.com/pub/suse/i386/update/8.2/rpm/i586/uucp-1.06.1-931.i586.rpm 1d5e50aea21f2ce88277fd9113dfb6da
patch rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.2/rpm/i586/uucp-1.06.1-931.i586.patch.rpm 402cff9f2e0e4b56b2409082d0adbc0d
source rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.2/rpm/src/sendmail-8.12.7-73.src.rpm 2cda6c535a3be4e26c50373bd078b4c7

SuSE-8.1:
ftp://ftp.suse.com/pub/suse/i386/update/8.1/rpm/i586/uucp-1.06.1-931.i586.rpm 7de06e8f16800359e25b5d9dcc739af5
patch rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.1/rpm/i586/uucp-1.06.1-931.i586.patch.rpm 67c84d8cd4ff132ef0c1a91ed845b5d8
source rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.1/rpm/src/sendmail-8.12.6-147.src.rpm 97417cee623251c6cc3009c13c5b1fbe

SuSE-8.0:
ftp://ftp.suse.com/pub/suse/i386/update/8.0/n4/uucp-1.06.1-931.i386.rpm b95b64d0c474ee7b37a82e2fc04e72b7
patch rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.0/n4/uucp-1.06.1-931.i386.patch.rpm e872341553634848bb19b0d89a1e3a37
source rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.0/zq1/sendmail-8.12.3-76.src.rpm 4c059b5714ba2dbe5860654622b65bfb


2) Pending vulnerabilities in SuSE Distributions and Workarounds:

  • 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 servers soon.
  • pam_smb A buffer overflow in the password handling function of pam_smb allows remote root compromise. Fixed packages will be available soon.
  • 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 servers.

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.
  3. 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 security@suse.de), 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.
  4. 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:
    1. gpg is installed
    2. 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 "build@suse.de" 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:

suse-security@suse.com

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

    <suse-security-subscribe@suse.com>.

suse-security-announce@suse.com

For general information or the frequently asked questions (faq) send mail to:

<suse-security-info@suse.com> or
<suse-security-faq@suse.com> respectively.


SuSE's security contact is <security@suse.com> or <security@suse.de>. The <security@suse.de> 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 <security@suse.de>
pub 1024D/9C800ACA 2000-10-19 SuSE Package Signing Key <build@suse.de>

Bye,

Thomas
--
Thomas Biege <thomas@suse.de>