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Gentoo Linux Security Advisory                           GLSA 200701-01
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                                            https://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:

  https://security.gentoo.org/glsa/200701-01

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
https://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.

https://creativecommons.org/licenses/by-sa/2.5/