6069967 2001-02-08 19:19 -0500  /51 rader/ Niels Provos <provos@CITI.UMICH.EDU>
Sänt av: joel@lysator.liu.se
Importerad: 2001-02-09  02:44  av Brevbäraren (som är implementerad i) Python
Extern mottagare: BUGTRAQ@SECURITYFOCUS.COM
Externa svar till: provos@CITI.UMICH.EDU
Mottagare: Bugtraq (import) <15318>
Ärende: Authentication By-Pass Vulnerability in OpenSSH-2.3.1 (devel
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 snapshot)
From: Niels Provos <provos@CITI.UMICH.EDU>
To: BUGTRAQ@SECURITYFOCUS.COM
Message-ID: <20010209001953.7A804207C1@citi.umich.edu>

Please, check http://www.openssh.com/security.html for a full summary
of security related issues in OpenSSH.

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                        OpenBSD Security Advisory

                            February 8, 2001

             Authentication By-Pass Vulnerability in OpenSSH-2.3.1

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SYNOPSIS

OpenSSH-2.3.1, a development snapshot, only checked if a public key
for public key authentication was permitted.  In the protocol 2 part
of the server, the challenge-response step that ensures that the
connecting client is in possession of the corresponding private key
has been omitted. As a result, anyone who could obtain the public key
listed in the users authorized_keys file could log in as that user
without authentication.

A fix for this problem was committed on Februrary 8th.  The problem
was introduced on January 18th.  This is a three week time window.

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AFFECTED SYSTEMS

This vulnerability affects only OpenSSH version 2.3.1 with support for
protocol 2 enabled.  The latest official release OpenSSH 2.3.0 is not
affected by this problem.  The latest snapshot version OpenSSH 2.3.2
is not affected either.

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RESOLUTION

If you installed the OpenSSH 2.3.1 development snapshot, install the
latest snapshot.  Currently, the latest snapshot is OpenSSH 2.3.2
which is available via http://www.openssh.com/.

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