SUSE Linux Advisory: Linux Kernel (x86_64, AMD64)
Jan 15, 2004, 00:57 (0 Talkback[s])
SUSE Security Announcement
||Linux Kernel (x86_64, AMD64)
||Monday, Jan 15th 2004 14:17 MET
||9.0 SuSE Linux Enterprise Server 8,
||local system compromise
|SUSE default package:
Content of this advisory:
- security vulnerability resolved:
- incorrect bounds checking in mremap()
- inproper CPU register access check in 32bit ptrace() problem
description, discussion, solution and upgrade information
- pending vulnerabilities, solutions, workarounds:
- XDM (XFree86, xf86)
- standard appendix (further information)
1) problem description, brief discussion, solution, upgrade
The do_mremap() function of the Linux Kernel is used to manage
(move, resize) Virtual Memory Areas (VMAs). By exploiting an
incorrect bounds check in do_mremap() during the remapping of
memory it is possible to create a VMA with the size of 0. In normal
operation do_mremap() leaves a memory hole of one page and creates
an additional VMA of two pages. In case of exploitation no hole is
created but the new VMA has a 0 bytes length. The Linux Kernel's
memory management is corrupted from this point and can be abused by
local users to gain root privileges.
Additionally Andi Kleen of SUSE LINUX found and fixed another
bug in the 32bit emulation of ptrace() which allows to modify CPU
registers from user-space to get full access to system
There is no temporary workaround for this bug.
Please reboot your system to run the new kernel.
2) Pending vulnerabilities in SUSE Distributions and
- ethereal Two remotely exploitable denial-of-service attacks
were found in the network analyzer ethereal. New packages are
available on our FTP servers.
- mc By using a special combination of links in archive-files it
is possible to execute arbitrary commands while mc tries to open it
in its VFS. The packages will be released soon.
- mod_gzip (apache-contrib) The apache module mod_gzip is
vulnerable to remote code execution while running in debug-mode. We
do not ship this module in debug-mode but future versions will
include the fix. Additionally the mod_gzip code was audited to fix
more possible security related bugs. After more testing a new
apache-contrib RPM package will be released.
- tripwire Tripwire is a file integrity checker. The tripwire
version on SuSE Linux 8.2 and 9.0 do crash when a requested file
does not exists. New packages will be available soon.
- cvs The cvs server-side can be tricked to create files in the
root filesystem of the server by requesting malformed modules. The
permissions on the root filesystem normally prevent this
malfunction. Additionally the package will include a fix for a
format-string bug. New packages are available on our FTP
- gnome-filesystem A script included in the gnome-filesystem
package handles temporary files insecurely. This script is called
by YaST2 with root privileges. The bug can be exploited locally to
create or overwrite arbitrary files in the filesystem. The bug is
fixed in our current source-tree since November 2003. New packages
are available on our FTP servers.
- XDM (XFree86, xf86) A missing check for failure conditions in
the PAM code of XDM can lead to local root access in conjunction
with Kerberos and alike. New packages will be released soon.
- 3ddiag Some 3ddiag scripts handle temporary files in an
insecure manner. Thanks to Stefan Nordhausen <nordhaus at
for reporting some of the issues. New packages will be available on
our FTP servers soon.
- mod_auth_shadow (apache-contrib) This apache module ignores
account expiration dates. The update will be released together with
3) standard appendix: authenticity verification, additional
- 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:
- md5sums as provided in the (cryptographically signed)
- using the internal gpg signatures of the rpm package.
- 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 firstname.lastname@example.org), 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.
- 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:
- gpg is installed
- 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@example.com"
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's security contact is <firstname.lastname@example.org> or
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.
||SuSE Security Team <email@example.com>
||SuSE Package Signing Key <firstname.lastname@example.org>