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AUSCERT External Security Bulletin Redistribution
ESB-2009.0163 -- [Win][UNIX/Linux]
OpenSSH 5.2 released
23 February 2009
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AusCERT Security Bulletin Summary
---------------------------------
Product: OpenSSH
Publisher: OpenSSH
Operating System: UNIX variants (UNIX, Linux, OSX)
Windows
Impact: Access Confidential Data
Access: Remote/Unauthenticated
Original Bulletin:
http://lists.mindrot.org/pipermail/openssh-unix-announce/2009-February/000096.html
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OpenSSH 5.2 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 version 1.3, 1.5 and 2.0
implementation and includes sftp client and server support.
We have also recently completed another Internet SSH usage scan, the
results of which may be found at http://www.openssh.com/usage.html
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
The focus of this release has been on bugfixes as the previous
openssh-5.1 release introduced many new features and made some
invasive changes.
Changes since OpenSSH 5.1
=========================
Security:
* This release changes the default cipher order to prefer the AES CTR
modes and the revised "arcfour256" mode to CBC mode ciphers that are
susceptible to CPNI-957037 "Plaintext Recovery Attack Against SSH".
* This release also adds countermeasures to mitigate CPNI-957037-style
attacks against the SSH protocol's use of CBC-mode ciphers. Upon
detection of an invalid packet length or Message Authentication
Code, ssh/sshd will continue reading up to the maximum supported
packet length rather than immediately terminating the connection.
This eliminates most of the known differences in behaviour that
leaked information about the plaintext of injected data which formed
the basis of this attack. We believe that these attacks are rendered
infeasible by these changes.
New features:
* Added a -y option to ssh(1) to force logging to syslog rather than
stderr, which is useful when running daemonised (ssh -f)
* The sshd_config(5) ForceCommand directive now accepts commandline
arguments for the internal-sftp server.
* The ssh(1) ~C escape commandline now support runtime creation of
dynamic (-D) port forwards.
* Support the SOCKS4A protocol in ssh(1) dynamic (-D) forwards.
(bz#1482)
* Support remote port forwarding with a listen port of '0'. This
informs the server that it should dynamically allocate a listen
port and report it back to the client. (bz#1003)
* sshd(8) now supports setting PermitEmptyPasswords and
AllowAgentForwarding in Match blocks
Bug and documentation fixes
* Repair a ssh(1) crash introduced in openssh-5.1 when the client is
sent a zero-length banner (bz#1496)
* Due to interoperability problems with certain
broken SSH implementations, the eow@openssh.com and
no-more-sessions@openssh.com protocol extensions are now only sent
to peers that identify themselves as OpenSSH.
* Make ssh(1) send the correct channel number for
SSH2_MSG_CHANNEL_SUCCESS and SSH2_MSG_CHANNEL_FAILURE messages to
avoid triggering 'Non-public channel' error messages on sshd(8) in
openssh-5.1.
* Avoid printing 'Non-public channel' warnings in sshd(8), since the
ssh(1) has sent incorrect channel numbers since ~2004 (this reverts
a behaviour introduced in openssh-5.1).
* Avoid double-free in ssh(1) ~C escape -L handler (bz#1539)
* Correct fail-on-error behaviour in sftp(1) batchmode for remote
stat operations. (bz#1541)
* Disable nonfunctional ssh(1) ~C escape handler in multiplex slave
connections. (bz#1543)
* Avoid hang in ssh(1) when attempting to connect to a server that
has MaxSessions=0 set.
* Multiple fixes to sshd(8) configuration test (-T) mode
* Several core and portable OpenSSH bugs fixed: 1380, 1412, 1418,
1419, 1421, 1490, 1491, 1492, 1514, 1515, 1518, 1520, 1538, 1540
* Many manual page improvements.
Checksums:
==========
- SHA1 (openssh-5.2.tar.gz) = 260074ed466e95f054ac05a4406f613d08575217
- SHA1 (openssh-5.2p1.tar.gz) = 8273a0237db98179fbdc412207ff8eb14ff3d6de
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.
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The University of Queensland
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