Date: Thu, 8 Feb 2001 19:19:53 -0500
From: Niels Provos <[email protected]>
To: [email protected]Subject: Authentication By-Pass Vulnerability in OpenSSH-2.3.1 (devel snapshot)
Please, check http://www.openssh.com/security.html for a full summary of
security related issues in OpenSSH.
----------------------------------------------------------------------------
OpenBSD Security Advisory
February 8, 2001
Authentication By-Pass Vulnerability in OpenSSH-2.3.1
----------------------------------------------------------------------------
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.
----------------------------------------------------------------------------
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.
----------------------------------------------------------------------------
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/.
----------------------------------------------------------------------------
