[UNIX] Multiple Vendor ypxfrd Map Handling Vulnerability

From: support@securiteam.com
Date: 10/11/02 

From: support@securiteam.com
To: list@securiteam.com
Date: 11 Oct 2002 14:04:40 +0200

The following security advisory is sent to the securiteam mailing list, and can be found at the SecuriTeam web site: http://www.securiteam.com
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  Multiple Vendor ypxfrd Map Handling Vulnerability
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SUMMARY

ypxfrd daemon is used for speed up the distribution of large NIS maps from
NIS master to NIS slave servers. An improper arguments validation in
ypxfrd may allow local attacker to read any file on the system. This
vulnerability has been found to affect multiple vendors.

DETAILS

When getdbm procedure is called, ypxfrd daemon creates a path to the
/var/yp/domain/map file (where domain and map are arguments provided in
the request). Unfortunately it fails to check if both arguments contain
slash or dot characters, thus making databases outside /var/yp directory
accessible. A symlink done can override the ".pag / .dir" file extension
limitation, allowing local attacker to read any file on the system.

The vendors were notified on August 27, 2002. The following systems are
identified as affected by this vulnerability:
 * Sun Microsystems Solaris
 * SCO OpenServer
 * Caldera OpenLinux

Impact:
When ypxfrd is configured and running, local attacker is able to read any
file on the system. As ypxfrd is typically run as root, this may lead to
privilege escalation. It is also possible to remotely read DBM files
outside /var/yp directory, depending on the secure networks configuration.

Vendor Response:
Please refer to CERT <http://www.kb.cert.org/vuls/id/538033> VU#538033
for more information.

ADDITIONAL INFORMATION

The original advisory can be downloaded by going to:
 <http://isec.pl/vulnerabilities/0006.txt>
http://isec.pl/vulnerabilities/0006.txt

The information has been provided by <mailto:funkysh@isec.pl> Janusz
Niewiadomski.

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