[Full-disclosure] [ GLSA 200701-01 ] DenyHosts: Denial of Service

[Raphael Marichez]

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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 at gentoo.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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