Updated: OpenSSH-7.1p2-1

Corinna Vinschen corinna-cygwin@cygwin.com
Fri Jan 15 15:05:00 GMT 2016


I've just updated the Cygwin version of OpenSSH to 7.1p2-1.

This is a security upstream release.

Below's the original release message.

Please note that the release message has a bug :)  The entry "SECURITY:
Eliminate the fallback from untrusted X11-forwarding ..." is wrong since
this change has been taken out of the 7.1p2 last-minute.

=========================================================================

OpenSSH 7.1p2 has just been released. It will be available from the
mirrors listed at http://www.openssh.com/ shortly.

OpenSSH is a 100% complete SSH protocol 2.0 implementation and
includes sftp client and server support. OpenSSH also includes
transitional support for the legacy SSH 1.3 and 1.5 protocols
that may be enabled at compile-time.

Once again, we would like to thank the OpenSSH community for their
continued support of the project, especially those who contributed
code or patches, reported bugs, tested snapshots or donated to the
project. More information on donations may be found at:
http://www.openssh.com/donations.html

Changes since OpenSSH 7.1p1
===========================

 * SECURITY: ssh(1): The OpenSSH client code between 5.4 and 7.1
   contains experimential support for resuming SSH-connections (roaming).

   The matching server code has never been shipped, but the client
   code was enabled by default and could be tricked by a malicious
   server into leaking client memory to the server, including private
   client user keys.

   The authentication of the server host key prevents exploitation
   by a man-in-the-middle, so this information leak is restricted
   to connections to malicious or compromised servers.

   MITIGATION: For OpenSSH >= 5.4 the vulnerable code in the client
   can be completely disabled by adding 'UseRoaming no' to the gobal
   ssh_config(5) file, or to user configuration in ~/.ssh/config,
   or by passing -oUseRoaming=no on the command line.

   PATCH: See below for a patch to disable this feature (Disabling
   Roaming in the Source Code).

   This problem was reported by the Qualys Security Advisory team.

 * SECURITY: Eliminate the fallback from untrusted X11-forwarding
   to trusted forwarding for cases when the X server disables
   the SECURITY extension. Reported by Thomas Hoger.

 * SECURITY: Fix an out of-bound read access in the packet handling
   code. Reported by Ben Hawkes.

 * PROTOCOL: Correctly interpret the 'first_kex_follows' option during
   the intial key exchange. Reported by Matt Johnston.

 * Further use of explicit_bzero has been added in various buffer
   handling code paths to guard against compilers aggressively
   doing dead-store removal.


Checksums:
==========

 - SHA1 (openssh-7.1p2.tar.gz) = 9202f5a2a50c8a55ecfb830609df1e1fde97f758
 - SHA256 (openssh-7.1p2.tar.gz) = dd75f024dcf21e06a0d6421d582690bf987a1f6323e32
ad6619392f3bfde6bbd

Please note that the SHA256 signatures are base64 encoded and not
hexadecimal (which is the default for most checksum tools). The PGP
key used to sign the releases is available as RELEASE_KEY.asc from
the mirror sites.

Reporting Bugs:
===============

- Please read http://www.openssh.com/report.html
  Security bugs should be reported directly to openssh@openssh.com

OpenSSH is brought to you by Markus Friedl, Niels Provos, Theo de Raadt,
Kevin Steves, Damien Miller, Darren Tucker, Jason McIntyre, Tim Rice and
Ben Lindstrom.

Disabling Roaming in the Source Code:
=====================================

--- readconf.c  30 Jul 2015 00:01:34 -0000	1.239
+++ readconf.c  13 Jan 2016 23:17:23 -0000
@@ -1648,7 +1648,7 @@ initialize_options(Options * options)
        options->tun_remote = -1;
        options->local_command = NULL;
        options->permit_local_command = -1;
-	options->use_roaming = -1;
+	options->use_roaming = 0;
        options->visual_host_key = -1;
        options->ip_qos_interactive = -1;
        options->ip_qos_bulk = -1;
@@ -1819,8 +1819,7 @@ fill_default_options(Options * options)
                options->tun_remote = SSH_TUNID_ANY;
        if (options->permit_local_command == -1)
                options->permit_local_command = 0;
-	if (options->use_roaming == -1)
-               options->use_roaming = 1;
+	options->use_roaming = 0;
        if (options->visual_host_key == -1)
                options->visual_host_key = 0;
        if (options->ip_qos_interactive == -1)
--- ssh.c	30 Jul 2015 00:01:34 -0000	1.420
+++ ssh.c	13 Jan 2016 23:17:23 -0000
@@ -1882,9 +1882,6 @@ ssh_session2(void)
                        fork_postauth();
       	}

-	if (options.use_roaming)
-               request_roaming();
-
        return client_loop(tty_flag, tty_flag ?
            options.escape_char : SSH_ESCAPECHAR_NONE, id);
 }

=========================================================================

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat



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