full-disclosure - [ GLSA 200609-17 ] OpenSSH: Denial of Service

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Date: Wed, 27 Sep 2006 19:02:12 +0200
From: Sune Kloppenborg Jeppesen <jaervosz@...too.org>
To: gentoo-announce@...too.org
Cc: full-disclosure@...ts.grok.org.uk, bugtraq@...urityfocus.com,
	security-alerts@...uxsecurity.com
Subject: [ GLSA 200609-17 ] OpenSSH: Denial of Service

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Gentoo Linux Security Advisory                           GLSA 200609-17
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                                            http://security.gentoo.org/
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  Severity: Normal
     Title: OpenSSH: Denial of Service
      Date: September 27, 2006
      Bugs: #148228
        ID: 200609-17

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Synopsis
========

A flaw in the OpenSSH daemon allows remote unauthenticated attackers to
cause a Denial of Service.

Background
==========

OpenSSH is a free suite of applications for the SSH protocol, developed
and maintained by the OpenBSD project.

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

    -------------------------------------------------------------------
     Package           /   Vulnerable   /                   Unaffected
    -------------------------------------------------------------------
  1  net-misc/openssh      < 4.3_p2-r5                    >= 4.3_p2-r5

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

Tavis Ormandy of the Google Security Team discovered a Denial of
Service vulnerability in the SSH protocol version 1 CRC compensation
attack detector.

Impact
======

A remote unauthenticated attacker may be able to trigger excessive CPU
usage by sending a pathological SSH message, denying service to other
legitimate users or processes.

Workaround
==========

The system administrator may disable SSH protocol version 1 in
/etc/ssh/sshd_config.

Resolution
==========

All OpenSSH users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=net-misc/openssh-4.3_p2-r3"

References
==========

  [ 1 ] CVE-2006-4924
        http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4924

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

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

  http://security.gentoo.org/glsa/glsa-200609-17.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 2006 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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