Characters expansion vulnerability

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CONECTIVA LINUX SECURITY ANNOUNCEMENT
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PACKAGE : dhcpcd
SUMMARY : Characters expansion vulnerability
DATE : 2002-11-18 19:28:00
ID : CLA-2002:549
RELEVANT
RELEASES : 6.0, 7.0, 8

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DESCRIPTION
dhcpcd is an RFC2131 and RFC1541 compliant DHCP client daemon.

dhcpcd has the ability to execute an external script named
/sbin/dhcpcd-<interface>.exe when assigning a new IP address to a
network interface. This script sources a file named
/var/lib/dhcpcd/dhcpcd-<interface>.info that contains several shell
variables and assigments with DHCP information.

Simon Kelley pointed out a vulnerability in the way quotes inside
these assignments are treated. By exploiting this, a malicious DHCP
server (or attackers able to spoof DHCP responses) can execute
arbitrary shell commands on the DHCP client (which is run by root).

The script /sbin/dhcpcd-<interface>.exe is not installed by default
in Conectiva Linux, but is included in the documentation directory of
the dhcpcd package. Please notice that it is possible to exploit this
vulnerability only if the user has installed the script manually.


SOLUTION
All dhcpcd users are advised to upgrade.

IMPORTANT NOTE: After the upgrade, dhcpcd must be restarted manually.
This can be accomplished by the command:

# service network restart

Please be careful if doing this remotely, since this will shutdown
and restart the network interfaces and potentially change their IP
address.


REFERENCES:
1.http://www.phystech.com/download/dhcpcd_changelog.html


DIRECT DOWNLOAD LINKS TO THE UPDATED PACKAGES
ftp://atualizacoes.conectiva.com.br/6.0/RPMS/dhcpcd-1.3.22pl3-1U60_2cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/6.0/SRPMS/dhcpcd-1.3.22pl3-1U60_2cl.src.rpm
ftp://atualizacoes.conectiva.com.br/7.0/RPMS/dhcpcd-1.3.22pl3-1U70_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/7.0/SRPMS/dhcpcd-1.3.22pl3-1U70_1cl.src.rpm
ftp://atualizacoes.conectiva.com.br/8/RPMS/dhcpcd-1.3.22pl3-1U80_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/8/SRPMS/dhcpcd-1.3.22pl3-1U80_1cl.src.rpm


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


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

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