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Home » Security Advisories» Gentoo » Shorewall security policy bypass

Shorewall security policy bypass

The "unaffected" version was incorrectly set to 2.4.1 in the initial advisory, the correct "unaffected" version is 2.4.2. A vulnerability in Shorewall allows clients authenticated by MAC address filtering to bypass all other security rules.

  • Vendor: Gentoo
  • Vendor ID: GLSA 200507-20:02
  • Date: September 14, 2005


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Gentoo Linux Security Advisory [ERRATA UPDATE] GLSA 200507-20:02
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http://security.gentoo.org/
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Severity: Low
Title: Shorewall: Security policy bypass
Date: July 22, 2005
Updated: September 14, 2005
Bugs: #99398
ID: 200507-20:02

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Errata
======

The "unaffected" version was incorrectly set to 2.4.1 in the initial
advisory, the correct "unaffected" version is 2.4.2.

The corrected sections appear below.

Synopsis
========

A vulnerability in Shorewall allows clients authenticated by MAC
address filtering to bypass all other security rules.

Background
==========

Shorewall is a high level tool for configuring Netfilter, the firewall
facility included in the Linux Kernel.

Affected packages
=================

-------------------------------------------------------------------
Package / Vulnerable / Unaffected
-------------------------------------------------------------------
1 net-firewall/shorewall <= 2.4.1 >= 2.4.2

Description
===========

Shorewall fails to enforce security policies if configured with
"MACLIST_DISPOSITION" set to "ACCEPT" or "MACLIST_TTL" set to a value
greater or equal to 0.

Impact
======

A client authenticated by MAC address filtering could bypass all
security policies, possibly allowing him to gain access to restricted
services. The default installation has MACLIST_DISPOSITION=REJECT and
MACLIST_TTL=(blank) (equivalent to 0). This can be checked by looking
at the settings in /etc/shorewall/shorewall.conf

Workaround
==========

Set "MACLIST_TTL" to "0" and "MACLIST_DISPOSITION" to "REJECT" in the
Shorewall configuration file (usually /etc/shorewall/shorewall.conf).

Resolution
==========

All Shorewall users should upgrade to the latest available version:

# emerge --sync
# emerge --ask --oneshot --verbose net-firewall/shorewall

References
==========

[ 1 ] CAN-2005-2317
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-2317
[ 2 ] Shorewall Announcement
http://www.shorewall.net/News.htm#20050717

Availability
============

This GLSA and any updates to it are available for viewing at
the Gentoo Security Website:

http://security.gentoo.org/glsa/glsa-200507-20.xml

Concerns?
=========

Security is a primary focus of Gentoo Linux and ensuring the
confidentiality and security of our users machines is of utmost
importance to us. Any security concerns should be addressed to
[email protected] or alternatively, you may file a bug at
http://bugs.gentoo.org.

License
=======

Copyright 2005 Gentoo Foundation, Inc; referenced text
belongs to its owner(s).

The contents of this document are licensed under the
Creative Commons - Attribution / Share Alike license.

http://creativecommons.org/licenses/by-sa/2.0

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