bugtraq - [ GLSA 200701-01 ] DenyHosts: Denial of Service

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Date: Wed, 3 Jan 2007 19:25:40 +0100
From: Raphael Marichez <falco@...too.org>
To: gentoo-announce@...too.org
Cc: bugtraq@...urityfocus.com, full-disclosure@...ts.grok.org.uk,
	security-alerts@...uxsecurity.com
Subject: [ GLSA 200701-01 ] DenyHosts: Denial of Service

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Gentoo Linux Security Advisory                           GLSA 200701-01
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                                            http://security.gentoo.org/
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  Severity: Normal
     Title: DenyHosts: Denial of Service
      Date: January 03, 2007
      Bugs: #157163
        ID: 200701-01

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Synopsis
========

DenyHosts does not correctly parse log entries, potentially causing a
remote Denial of Service.

Background
==========

DenyHosts is designed to monitor SSH servers for repeated failed login
attempts.

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

    -------------------------------------------------------------------
     Package              /  Vulnerable  /                  Unaffected
    -------------------------------------------------------------------
  1  app-admin/denyhosts        < 2.6                           >= 2.6

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

Tavis Ormandy of the Gentoo Linux Security Audit Team discovered that
DenyHosts used an incomplete regular expression to parse failed login
attempts.

Impact
======

A remote unauthenticated attacker can add arbitrary hosts to the
blacklist by attempting to login with a specially crafted username. An
attacker may use this to prevent legitimate users from accessing a host
remotely.

Workaround
==========

There is no known workaround at this time.

Resolution
==========

All DenyHosts users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=app-admin/denyhosts-2.6"

References
==========

  [ 1 ] CVE-2006-6301
        http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-6301

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

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

  http://security.gentoo.org/glsa/glsa-200701-01.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@...too.org or alternatively, you may file a bug at
http://bugs.gentoo.org.

License
=======

Copyright 2007 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/2.5

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