Gentoo: Shorewall Security policy bypass
Posted by Benjamin D. Thomas   
Gentoo A vulnerability in Shorewall allows clients authenticated by MAC address filtering to bypass all other security rules.
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Gentoo Linux Security Advisory                           GLSA 200507-20
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                                            http://security.gentoo.org/
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  Severity: Low
     Title: Shorewall: Security policy bypass
      Date: July 22, 2005
      Bugs: #99398
        ID: 200507-20

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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                    *>= 2.2.5
                                                              >= 2.4.1

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.

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
security@gentoo.org 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