Users login

Create an account »

JOIN XATRIX

Users login

Home » Hacking News » SuSE-SA:2002:017-shadow/pam-modules

SuSE-SA:2002:017-shadow/pam-modules

by Nikola Strahija on May 16th, 2002 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
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 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 .

[email protected]
- SuSE's announce-only mailing list.
Only SuSE's security annoucements 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 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
pub 1024D/9C800ACA 2000-10-19 SuSE Package Signing Key

- -----BEGIN PGP PUBLIC KEY BLOCK-----
Version: GnuPG v1.0.6 (GNU/Linux)
Comment: For info see http://www.gnupg.org


Newsletter signup

Signup to our monthly newsletter and stay in touch with IT news!

Free E-books

We've got ebooks! But they're not online. :( Please give us a few days to bring downloads back.

Contact

Have something to say or just wanna drop us a line? Please keep this in mind: to spam, we reply with spam.

Contact us »