Bugtraq: gzip directory traversal vulnerability

[Imran Ghory <imranghory () gmail com>]

================================
gzip directory traversal vulnerability
================================

Software: gzip
Version: 1.2.4, 1.3.3
Software URL: <http://www.gzip.org>
Platform:  Unix, Linux.
Vulnerability type: Input validation
Severity: Medium, local vuln, requires user using gunzip -N on a
malicious zip file. Can result in privilege escalation.

Vulnerable software
====================

gzip 1.2.4 and 1.3.3 and previous versions running on unix.

Vulnerability
==============

Ulf Härnhammar <metaur () telia com> has discovered a vulnerability in
gunzip that allows a malicious zip file to extract to an arbitrary
directory of the attackers choice when gunzip is used with the -N
option.

Further details of this vulnerability are available in the Debian bug
report #305255.

Direct link: <http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=305255>

This vulnerability can be used to make the gzip file extract to a
directory which the attacker has write access to. This vulnerability
then be used in combination with the gzip TOCTOU file-permissions
vulnerability (CAN-2005-0988, Bugtraq #12996) to change the
permissions on arbitrary files belonging to the user.

Fix
====

A patch developed by Ulf Härnhammar is linked to from the bug report
link given above.