bugtraq - [ GLSA 200611-06 ] OpenSSH: Multiple Denial of Service vulnerabilities

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Date: Mon, 13 Nov 2006 23:53:37 +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 200611-06 ] OpenSSH: Multiple Denial of Service vulnerabilities

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Gentoo Linux Security Advisory                           GLSA 200611-06
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                                            http://security.gentoo.org/
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  Severity: Normal
     Title: OpenSSH: Multiple Denial of Service vulnerabilities
      Date: November 13, 2006
      Bugs: #149502
        ID: 200611-06

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Synopsis
========

Several Denial of Service vulnerabilities have been identified in
OpenSSH.

Background
==========

OpenSSH is a complete SSH protocol version 1.3, 1.5 and 2.0
implementation and includes sftp client and server support.

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

    -------------------------------------------------------------------
     Package           /   Vulnerable   /                   Unaffected
    -------------------------------------------------------------------
  1  net-misc/openssh      < 4.4_p1-r5                    >= 4.4_p1-r5

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

Tavis Ormandy of the Google Security Team has discovered a
pre-authentication vulnerability, causing sshd to spin until the login
grace time has been expired. Mark Dowd found an unsafe signal handler
that was vulnerable to a race condition. It has also been discovered
that when GSSAPI authentication is enabled, GSSAPI will in certain
cases incorrectly abort.

Impact
======

The pre-authentication and signal handler vulnerabilities can cause a
Denial of Service in OpenSSH. The vulnerability in the GSSAPI
authentication abort could be used to determine the validity of
usernames on some platforms.

Workaround
==========

There is no known workaround at this time.

Resolution
==========

All OpenSSH users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=net-misc/openssh-4.4_p1-r5"

References
==========

  [ 1 ] CVE-2006-5051
        http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-5051
  [ 2 ] CVE-2006-5052
        http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-5052
  [ 3 ] OpenSSH Security Advisory
        http://www.openssh.com/txt/release-4.4

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

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

  http://security.gentoo.org/glsa/glsa-200611-06.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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