[CLA-2002:529] Conectiva Linux Security Announcement - XFree86

2002-10-0400:00:00

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CONECTIVA LINUX SECURITY ANNOUNCEMENT

PACKAGE : XFree86
SUMMARY : Local vulnerabilities
DATE : 2002-10-03 14:17:00
ID : CLA-2002:529
RELEVANT
RELEASES : 8

DESCRIPTION
XFree86 is a freely redistributable open-source implementation of the
X Window System, which is a client/server interface between display
hardware and the desktop environment. Xlib is one of the main
libraries of XFree86 (libX11.so.6).

This update adresses two vulnerabilities in XFree86:

XLib i18n vulnerability

XFree86-4.2.0 added a functionality to the Xlib which allows it to
load modules from paths controled by the user during the startup of
programs linked against it. The vulnerability[1] exists because Xlib
does not check if the program being started is SUID, thus allowing
arbitrary code to be run with the other users' privileges

By exploiting this vulnerability a malicious user can get aditional
privileges on the system. In the worst case, he/she can run arbitrary
code as root if there are SUID root programs linked against Xlib.

Althought we were not able to sucessfuly run any exploit, there are
some SUID root programs linked against Xlib in Conectiva Linux 8
which are potentially vulnerable.

Conectiva Linux 6.0 (XFree86-4.0.1) and Conectiva Linux 7.0
(XFree86-4.0.3) are not vulnerable.

MIT-SHM extension vulnerability

Roberto Zunino discovered a vulnerability in the MIT-SHM extension of
XFree86 prior to versions 4.2.1. The vulnerability allows a local
user who can run XFree86 to gain read/write access to any shared
memory segment in the system. Although the use of shared memory
segments to store trusted data is not a common practice, by
exploiting this vulnerability the attacker potentially can get and/or
change sensitive information.

This vulnerability also affects Conectiva Linux version 6.0 and 7.0,
and a new update for these versions will be available in the next
days.

SOLUTION
All XFree86 users should upgrade.

Users of Conectiva Linux 6.0 and 7.0 are still vulnerable to the
MIT-SHM extension vulnerability and should wait for a new update in a
few days.

REFERENCES:

http://www.xfree86.org/security/

ADDITIONAL INSTRUCTIONS
Users of Conectiva Linux version 6.0 or higher may use apt to perform
upgrades of RPM packages:

add the following line to /etc/apt/sources.list if it is not there yet
(you may also use linuxconf to do this):

rpm [cncbr] ftp://atualizacoes.conectiva.com.br 6.0/conectiva updates

(replace 6.0 with the correct version number if you are not running CL6.0)

run: apt-get update
after that, execute: apt-get upgrade

Detailed instructions reagarding the use of apt and upgrade examples
can be found at http://distro.conectiva.com.br/atualizacoes/#apt?idioma=en

All packages are signed with Conectiva's GPG key. The key and instructions
on how to import it can be found at
http://distro.conectiva.com.br/seguranca/chave/?idioma=en
Instructions on how to check the signatures of the RPM packages can be
found at http://distro.conectiva.com.br/seguranca/politica/?idioma=en

All our advisories and generic update instructions can be viewed at
http://distro.conectiva.com.br/atualizacoes/?idioma=en

subscribe: [email protected]
unsubscribe: [email protected]
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