SuSE Security Announcement: shadow (SuSE-SA:2002:017)

2002-05-17T00:00:00
ID SECURITYVULNS:DOC:2946
Type securityvulns
Reporter Securityvulns
Modified 2002-05-17T00:00:00

Description

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


                    SuSE Security Announcement

    Package:                shadow/pam-modules
    Announcement-ID:        SuSE-SA:2002:017
    Date:                   Thu May 16 12:00:00 MEST 2002
    Affected products:      8.0
    Vulnerability Type:     local privilege escalation
    Severity (1-10):        5
    SuSE default package:   yes
    Other affected systems: No.

Content of this advisory:
    1) security vulnerability resolved: write() disruption in shadow utils
       problem description, discussion, solution and upgrade information
    2) pending vulnerabilities, solutions, workarounds
    3) standard appendix (further information)

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

The shadow package contains several useful programs to maintain the
entries in the /etc/passwd and /etc/shadow files.
    The SuSE Security Team discovered a vulnerability that allows local
attackers to destroy the contents of these files or to extend the group
privileges of certain users. This is possible by setting evil filesize
limits before invoking one of the programs modifying the system files.
Depening on the permissions of the system binaries this allows a local
attacker to gain root privileges in the worst case. This however is not
possible in a default installation.
    The bug has been fixed by ensuring the integrity of the data written
to temporary files before moving them to the appropriate location of the
system. There is no workaround so we recommend an update in any case.
It is necessary to update the shadow package as well as the pam-modules
package in order to prevent the truncation attacks.

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.


i386 Intel Platform:

SuSE-8.0
ftp://ftp.suse.com/pub/suse/i386/update/8.0/a1/shadow-4.0.2-88.i386.rpm
  a4e0d03ecf7707eb7ca1f0422cae89f1

ftp://ftp.suse.com/pub/suse/i386/update/8.0/a1/pam-modules-2002.3.9-31.i386.rpm 70322584f014ac3e2dc2dad0beecdefb

source rpm:
ftp://ftp.suse.com/pub/suse/i386/update/8.0/zq1/shadow-4.0.2-88.src.rpm
  33af2433d9a8822202e9f6ebdc6d3e2c

ftp://ftp.suse.com/pub/suse/i386/update/8.0/zq1/pam-modules-2002.3.9-31.src.rpm 1bc5bbd169ffe5c35caa0a4ce681dcc0


2) Pending vulnerabilities in SuSE Distributions and Workarounds:

- leafnode
The permissions of "/etc/leafnode" have been corrected. Please update
to the newly available packages if you use leafnode.

- xf86, xmodules, xloader
Incorrect permission checks in certain X11 functions allow local attackers
to read or write shared memory segments they should not have access to.
Corrected packages will soon be 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.

    1) 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.

    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 uninstalled 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 "build@suse.de" upon installation or upgrade, provided that the package gpg is installed. The file containing the public key is placed at the toplevel 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 - SuSE's announce-only mailing list. Only SuSE's security annoucements are sent to this list. To subscribe, send an email to <suse-security-announce-subscribe@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 cleartext 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>

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-- ~ ~ perl self.pl ~ $='print"\$=\47$_\47;eval"';eval ~ krahmer@suse.de - SuSE Security Team ~