Scientific Linux Security Update : openssh on SL6.x i386/x86_64

This script is Copyright (C) 2013 Tenable Network Security, Inc.


Synopsis :

The remote Scientific Linux host is missing one or more security
updates.

Description :

Due to the way the pam_ssh_agent_auth PAM module was built in
Scientific Linux 6, the glibc's error() function was called rather
than the intended error() function in pam_ssh_agent_auth to report
errors. As these two functions expect different arguments, it was
possible for an attacker to cause an application using
pam_ssh_agent_auth to crash, disclose portions of its memory or,
potentially, execute arbitrary code. (CVE-2012-5536)

Note that the pam_ssh_agent_auth module is not used in Scientific
Linux 6 by default.

This update also fixes the following bugs :

- All possible options for the new RequiredAuthentications
directive were not documented in the sshd_config man
page. This update improves the man page to document all
the possible options.

- When stopping one instance of the SSH daemon (sshd), the
sshd init script (/etc/rc.d/init.d/sshd) stopped all
sshd processes regardless of the PID of the processes.
This update improves the init script so that it only
kills processes with the relevant PID. As a result, the
init script now works more reliably in a multi-instance
environment.

- Due to a regression, the ssh-copy-id command returned an
exit status code of zero even if there was an error in
copying the key to a remote host. With this update, a
patch has been applied and ssh-copy-id now returns a
non-zero exit code if there is an error in copying the
SSH certificate to a remote host.

- When SELinux was disabled on the system, no on-disk
policy was installed, a user account was used for a
connection, and no '~/.ssh' configuration was present in
that user's home directory, the SSH client terminated
unexpectedly with a segmentation fault when attempting
to connect to another system. A patch has been provided
to address this issue and the crashes no longer occur in
the described scenario.

- The 'HOWTO' document
/usr/share/doc/openssh-ldap-5.3p1/HOWTO.ldap-keys
incorrectly documented the use of the
AuthorizedKeysCommand directive. This update corrects
the document.

This update also adds the following enhancements :

- When attempting to enable SSH for use with a Common
Access Card (CAC), the ssh-agent utility read all the
certificates in the card even though only the ID
certificate was needed. Consequently, if a user entered
their PIN incorrectly, then the CAC was locked, as a
match for the PIN was attempted against all three
certificates. With this update, ssh-add does not try the
same PIN for every certificate if the PIN fails for the
first one. As a result, the CAC will not be disabled if
a user enters their PIN incorrectly.

- This update adds a 'netcat mode' to SSH. The 'ssh -W
host:port ...' command connects standard input and
output (stdio) on a client to a single port on a server.
As a result, SSH can be used to route connections via
intermediate servers.

- Due to a bug, arguments for the RequiredAuthentications2
directive were not stored in a Match block.
Consequently, parsing of the config file was not in
accordance with the man sshd_config documentation. This
update fixes the bug and users can now use the required
authentication feature to specify a list of
authentication methods as expected according to the man
page.

After installing this update, the OpenSSH server daemon (sshd) will be
restarted automatically.

See also :

http://www.nessus.org/u?da71c5e4

Solution :

Update the affected packages.

Risk factor :

Medium / CVSS Base Score : 6.2
(CVSS2#AV:L/AC:H/Au:N/C:C/I:C/A:C)

Family: Scientific Linux Local Security Checks

Nessus Plugin ID: 64954 ()

Bugtraq ID:

CVE ID: CVE-2012-5536