Moderate CentOS openssh Security Update


openssh-5.3p1-104.el6.i686.rpm, openssh-5.3p1-104.el6.src.rpm, openssh-5.3p1-104.el6.x86_64.rpm, openssh-askpass-5.3p1-104.el6.i686.rpm, openssh-askpass-5.3p1-104.el6.x86_64.rpm, openssh-clients-5.3p1-104.el6.i686.rpm, openssh-clients-5.3p1-104.el6.x86_64.rpm, openssh-ldap-5.3p1-104.el6.i686.rpm, openssh-ldap-5.3p1-104.el6.x86_64.rpm, openssh-server-5.3p1-104.el6.i686.rpm, openssh-server-5.3p1-104.el6.x86_64.rpm, pam_ssh_agent_auth-0.9.3-104.el6.i686.rpm, pam_ssh_agent_auth-0.9.3-104.el6.x86_64.rpm,
2018-01-18 11:08
2017-07-27 19:07
2017-04-01 19:08
2017-01-05 20:12


Updated openssh packages that fix two security issues, several bugs, and
add various enhancements are now available for Red Hat Enterprise Linux 6.

Red Hat Product Security has rated this update as having Moderate security
impact. Common Vulnerability Scoring System (CVSS) base scores, which give
detailed severity ratings, are available for each vulnerability from the
CVE links in the References section.

OpenSSH is OpenBSD's SSH (Secure Shell) protocol implementation.
These packages include the core files necessary for both the OpenSSH client
and server.

It was discovered that OpenSSH clients did not correctly verify DNS SSHFP
records. A malicious server could use this flaw to force a connecting
client to skip the DNS SSHFP record check and require the user to perform
manual host verification of the DNS SSHFP record. (CVE-2014-2653)

It was found that OpenSSH did not properly handle certain AcceptEnv
parameter values with wildcard characters. A remote attacker could use this
flaw to bypass intended environment variable restrictions. (CVE-2014-2532)

This update also fixes the following bugs:

* Based on the SP800-131A information security standard, the generation of
a digital signature using the Digital Signature Algorithm (DSA) with the
key size of 1024 bits and RSA with the key size of less than 2048 bits is
disallowed after the year 2013. After this update, ssh-keygen no longer
generates keys with less than 2048 bits in FIPS mode. However, the sshd
service accepts keys of size 1024 bits as well as larger keys for
compatibility reasons. (BZ#993580)

* Previously, the openssh utility incorrectly set the oom_adj value to -17
for all of its children processes. This behavior was incorrect because the
children processes were supposed to have this value set to 0. This update
applies a patch to fix this bug and oom_adj is now properly set to 0 for
all children processes as expected. (BZ#1010429)

* Previously, if the sshd service failed to verify the checksum of an
installed FIPS module using the fipscheck library, the information about
this failure was only provided at the standard error output of sshd. As a
consequence, the user could not notice this message and be uninformed when
a system had not been properly configured for FIPS mode. To fix this bug,
this behavior has been changed and sshd now sends such messages via the
syslog service. (BZ#1020803)

* When keys provided by the pkcs11 library were removed from the ssh agent
using the "ssh-add -e" command, the user was prompted to enter a PIN.
With this update, a patch has been applied to allow the user to remove the
keys provided by pkcs11 without the PIN. (BZ#1042519)

In addition, this update adds the following enhancements:

* With this update, ControlPersist has been added to OpenSSH. The option in
conjunction with the ControlMaster configuration directive specifies that
the master connection remains open in the background after the initial
client connection has been closed. (BZ#953088)

* When the sshd daemon is configured to force the internal SFTP session,
and the user attempts to use a connection other than SFTP, the appropriate
message is logged to the /var/log/secure file. (BZ#997377)

* Support for Elliptic Curve Cryptography modes for key exchange (ECDH) and
host user keys (ECDSA) as specified by RFC5656 has been added to the
openssh packages. However, they are not enabled by default and the user has
to enable them manually. For more information on how to configure ECDSA and
ECDH with OpenSSH, see:

All openssh users are advised to upgrade to these updated packages, which
contain backported patches to correct these issues and add these
Please see

Am I vulnerable?

The constraints below list the versions that this vulnerability is patched in, and versions that are unaffected. If a patch is ready but unrealeased, then it is pending.

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Affected package information

Release Package Patched in
6 openssh openssh-5.3p1-104.el6.i686.rpm
openssh openssh-5.3p1-104.el6.src.rpm
openssh openssh-5.3p1-104.el6.x86_64.rpm
openssh-askpass openssh-askpass-5.3p1-104.el6.i686.rpm
openssh-askpass openssh-askpass-5.3p1-104.el6.x86_64.rpm
openssh-clients openssh-clients-5.3p1-104.el6.i686.rpm
openssh-clients openssh-clients-5.3p1-104.el6.x86_64.rpm
openssh-ldap openssh-ldap-5.3p1-104.el6.i686.rpm
openssh-ldap openssh-ldap-5.3p1-104.el6.x86_64.rpm
openssh-server openssh-server-5.3p1-104.el6.i686.rpm
openssh-server openssh-server-5.3p1-104.el6.x86_64.rpm
pam_ssh_agent_auth pam_ssh_agent_auth-0.9.3-104.el6.i686.rpm
pam_ssh_agent_auth pam_ssh_agent_auth-0.9.3-104.el6.x86_64.rpm