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Home » Hacking News » CLA-2002:483-Format string vulnerability

CLA-2002:483-Format string vulnerability

by Nikola Strahija on May 9th, 2002 "dhcp" is a Dynamic Host Configuration Protocol Server and Client. Versions ranging from 3 to 3.0.1rc8 (inclusive) have a format string vulnerability[1] that could be exploited remotely. Considering the usage of the DHCP service, this usually means the local area network in this case.


By default, these versions of DHCP are compiled with the dns update
feature enabled. This feature allows the DHCP service to update dns
records. The code in DHCP that logs this update has a format string
vulnerability that could be exploited, since the update message
contains data provided by the attacker, such as a hostname. A
successful exploitation would give an attacker the same privileges
the DHCP daemon has, tipically root.

This vulnerability was discovered and researched by Fermín J. Serna
from Next Generation Security Technologies[2] and
published in coordination with CERT.


SOLUTION
All dhcp users should upgrade immediately. After upgrading the
packages, manually restart the dhcp server with the following
command:

service dhcpd restart


REFERENCES
1. http://www.cert.org/advisories/CA-2002-12.html
2. http://www.ngsec.com/docs/advisories/NGSEC-2002-2.txt
3. http://www.isc.org/


DIRECT DOWNLOAD LINKS TO THE UPDATED PACKAGES
ftp://atualizacoes.conectiva.com.br/8/SRPMS/dhcp-3.0-3U8_1cl.src.rpm
ftp://atualizacoes.conectiva.com.br/8/RPMS/dhcp-3.0-3U8_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/8/RPMS/dhcp-doc-3.0-3U8_1cl.i386.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


- -------------------------------------------------------------------------
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

- -------------------------------------------------------------------------
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