Authentication By-Pass Vulnerability in OpenSSH 2.3.1 (devel snapshot) (fwd)

Authentication By-Pass Vulnerability in OpenSSH 2.3.1 (devel snapshot) (fwd)

[Corinna Vinschen]

FYI for those running snapshots.  I have removed the openssh-20010202
snapshot from cygwin/latest.

If you are using the openssh-20010202 snapshot PLEASE REVERT BACK TO
openssh-20001221 OR openssh-2.3.0p1.!!!

Corinna

---------- Forwarded message ----------
Date: Thu, 08 Feb 2001 18:15:00 -0500
From: Niels Provos <provos@citi.umich.edu>
To: security-announce@openbsd.org
Subject: Authentication By-Pass Vulnerability in OpenSSH 2.3.1 (devel
    snapshot)

----------------------------------------------------------------------------

                        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/ .

----------------------------------------------------------------------------


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Re: Authentication By-Pass Vulnerability in OpenSSH 2.3.1 (devel snapshot) (fwd)

[Charles Wilson]

Corinna Vinschen wrote:
> FYI for those running snapshots.  I have removed the openssh-20010202
> snapshot from cygwin/latest.
> 
> If you are using the openssh-20010202 snapshot PLEASE REVERT BACK TO
> openssh-20001221 OR openssh-2.3.0p1.!!!

This means you have to re-regenerate your RSA keys after reverting back
to the older version, right?

--Chuck

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Re: Authentication By-Pass Vulnerability in OpenSSH 2.3.1 (devel snapshot) (fwd)

[Corinna Vinschen]

On Fri, Feb 09, 2001 at 03:17:55AM -0500, Charles Wilson wrote:
> Corinna Vinschen wrote:
> > FYI for those running snapshots.  I have removed the openssh-20010202
> > snapshot from cygwin/latest.
> > 
> > If you are using the openssh-20010202 snapshot PLEASE REVERT BACK TO
> > openssh-20001221 OR openssh-2.3.0p1.!!!
> 
> This means you have to re-regenerate your RSA keys after reverting back
> to the older version, right?

Right, but only the SSH2 RSA keys, not the SSH1 keys. Or you drop
usage of SSH2 RSA until the next official OpenSSH is released.

Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Developer                                mailto:cygwin@cygwin.com
Red Hat, Inc.

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Re: Authentication By-Pass Vulnerability in OpenSSH 2.3.1 (develsnapshot) (fwd)

[Mark Paulus]

Do I need to do this, if I only use the ssh client??  I had a problem with 2.3.0p1,
where it wouldn't connect to my machine @ home through my Netgear
router/firewall.  However, the latest snapshot I downloaded allows me to
connect.  I don't want to back off and lose my ability to connect unless
you are going to kill me if I don't.    



On Fri, 09 Feb 2001 08:40:18 +0100, Corinna Vinschen wrote:

>FYI for those running snapshots.  I have removed the openssh-20010202
>snapshot from cygwin/latest.
>
>If you are using the openssh-20010202 snapshot PLEASE REVERT BACK TO
>openssh-20001221 OR openssh-2.3.0p1.!!!
>
>Corinna
>
>---------- Forwarded message ----------
>Date: Thu, 08 Feb 2001 18:15:00 -0500
>From: Niels Provos <provos@citi.umich.edu>
>To: security-announce@openbsd.org
>Subject: Authentication By-Pass Vulnerability in OpenSSH 2.3.1 (devel
>    snapshot)
>
>----------------------------------------------------------------------------
>
>                        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/ .
>
>----------------------------------------------------------------------------
>
>
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>Check out: http://cygwin.com/ml/#unsubscribe-simple
>




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Re: Authentication By-Pass Vulnerability in OpenSSH 2.3.1 (devel snapshot) (fwd)

[Corinna Vinschen]

On Mon, Feb 12, 2001 at 02:42:10PM -0700, Mark Paulus wrote:
> Do I need to do this, if I only use the ssh client??  I had a problem with 2.3.0p1,
> where it wouldn't connect to my machine @ home through my Netgear
> router/firewall.  However, the latest snapshot I downloaded allows me to
> connect.  I don't want to back off and lose my ability to connect unless
> you are going to kill me if I don't.    

I would never kill you for any reason.

Security is everyone's own purpose. The OpenSSH team has decided
to remove all dangerous snapshots from their site. So did I.

As long as you don't use sshd it should be ok.

Corinna

> On Fri, 09 Feb 2001 08:40:18 +0100, Corinna Vinschen wrote:
> 
> >FYI for those running snapshots.  I have removed the openssh-20010202
> >snapshot from cygwin/latest.
> >
> >If you are using the openssh-20010202 snapshot PLEASE REVERT BACK TO
> >openssh-20001221 OR openssh-2.3.0p1.!!!
> >
> >Corinna
> >
> >---------- Forwarded message ----------
> >Date: Thu, 08 Feb 2001 18:15:00 -0500
> >From: Niels Provos <provos@citi.umich.edu>
> >To: security-announce@openbsd.org
> >Subject: Authentication By-Pass Vulnerability in OpenSSH 2.3.1 (devel
> >    snapshot)
> >
> >----------------------------------------------------------------------------
> >
> >                        OpenBSD Security Advisory
> >
> >                            February 8, 2001
> >
> >             Authentication By-Pass Vulnerability in OpenSSH-2.3.1
> >
> >----------------------------------------------------------------------------
> >[...]

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Developer                                mailto:cygwin@cygwin.com
Red Hat, Inc.

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