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AUSCERT External Security Bulletin Redistribution
ESB-2006.0094 -- [Win][UNIX/Linux]
OpenSSH 4.3 released
2 February 2006
AusCERT Security Bulletin Summary
Operating System: UNIX variants (UNIX, Linux, OSX)
Impact: Execute Arbitrary Code/Commands
Access: Existing Account
CVE Names: CVE-2006-0225
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OpenSSH 4.3 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 and purchased
T-shirts or posters.
T-shirt, poster and CD sales directly support the project. Pictures
and more information can be found at:
For international orders use http://https.openbsd.org/cgi-bin/order
and for European orders, use http://https.openbsd.org/cgi-bin/order.eu
Changes since OpenSSH 4.2:
Security bugs resolved in this release:
* CVE-2006-0225: scp (as does rcp, on which it is based) invoked a
subshell to perform local to local, and remote to remote copy
operations. This subshell exposed filenames to shell expansion
twice; allowing a local attacker to create filenames containing
shell metacharacters that, if matched by a wildcard, could lead
to execution of attacker-specified commands with the privilege of
the user running scp (Bugzilla #1094)
This is primarily a bug-fix release, only one new feature has been
* Add support for tunneling arbitrary network packets over a
connection between an OpenSSH client and server via tun(4) virtual
network interfaces. This allows the use of OpenSSH (4.3+) to create
a true VPN between the client and server providing real network
connectivity at layer 2 or 3. This feature is experimental and is
currently supported on OpenBSD, Linux, NetBSD (IPv4 only) and
FreeBSD. Other operating systems with tun/tap interface capability
may be added in future portable OpenSSH releases. Please refer to
the README.tun file in the source distribution for further details
and usage examples.
Some of the other bugs resolved and internal improvements are:
* Reduce default key length for new DSA keys generated by ssh-keygen
back to 1024 bits. DSA is not specified for longer lengths and does
not fully benefit from simply making keys longer. As per FIPS 186-2
Change Notice 1, ssh-keygen will refuse to generate a new DSA key
smaller or larger than 1024 bits
* Fixed X forwarding failing to start when a the X11 client is executed
in background at the time of session exit (Bugzilla #1086)
* Change ssh-keygen to generate a protocol 2 RSA key when invoked
without arguments (Bugzilla #1064)
* Fix timing variance for valid vs. invalid accounts when attempting
Kerberos authentication (Bugzilla #975)
* Ensure that ssh always returns code 255 on internal error (Bugzilla
* Cleanup wtmp files on SIGTERM when not using privsep (Bugzilla #1029)
* Set SO_REUSEADDR on X11 listeners to avoid problems caused by
lingering sockets from previous session (X11 applications can
sometimes not connect to 127.0.0.1:60xx) (Bugzilla #1076)
* Ensure that fds 0, 1 and 2 are always attached in all programs, by
duping /dev/null to them if necessary.
* Xauth list invocation had bogus "." argument (Bugzilla #1082)
* Remove internal assumptions on key exchange hash algorithm and output
length, preparing OpenSSH for KEX methods with alternate hashes.
* Ignore junk sent by a server before it sends the "SSH-" banner
* The manpages has been significantly improves and rearranged, in
addition to other specific manpage fixes:
#1037 - Man page entries for -L and -R should mention -g.
#1077 - Descriptions for "ssh -D" and DynamicForward should mention
they can specify "bind_address" optionally.
#1088 - Incorrect descriptions in ssh_config man page for
#1121 - Several corrections for ssh_agent manpages
* Lots of cleanups, including fixes to memory leaks on error paths
(Bugzilla #1109, #1110, #1111 and more) and possible crashes (#1092)
* Portable OpenSSH-specific fixes:
- Pass random seed during re-exec for each connection: speeds up
processing of new connections on platforms using the OpenSSH's
builtin entropy collector (ssh-rand-helper)
- PAM fixes and improvements:
#1045 - Missing option for ignoring the /etc/nologin file
#1087 - Show PAM password expiry message from LDAP on login
#1028 - Forward final non-query conversations to client
#1126 - Prevent user from being forced to change an expired
password repeatedly on AIX in some PAM configurations.
#1045 - Do not check /etc/nologin when PAM is enabled, instead
allow PAM to handle it. Note that on platforms using
PAM, the pam_nologin module should be used in sshd's
session stack in order to maintain past behaviour
- Portability-related fixes:
#989 - Fix multiplexing regress test on Solaris
#1097 - Cross-compile fixes.
#1096 - ssh-keygen broken on HPUX.
#1098 - $MAIL being set incorrectly for HPUX server login.
#1104 - Compile error on Tru64 Unix 4.0f
#1106 - Updated .spec file and startup for SuSE.
#1122 - Use _GNU_SOURCE define in favor of __USE_GNU, fixing
compilation problems on glibc 2.4
Thanks to everyone who has contributed patches, reported bugs or test
- - SHA1 (openssh-4.3.tar.gz) = 0cb66e56805d66b51511455423bab88aa58a1455
- - SHA1 (openssh-4.3p1.tar.gz) = b1f379127829e7e820955b2825130edd1601ba59
- - please read http://www.openssh.com/report.html
OpenSSH is brought to you by Markus Friedl, Niels Provos, Theo de Raadt,
Kevin Steves, Damien Miller, Darren Tucker, Jason McIntyre, Tim Rice and
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