[RHSA-2015:2088-06] Moderate: openssh security, bug fix, and enhancement update

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Red Hat Security Advisory

 

Synopsis: Moderate: openssh security, bug fix, and enhancement update

Advisory ID: RHSA-2015:2088-06

Product: Red Hat Enterprise Linux

Advisory URL: https://rhn.redhat.com/errata/RHSA-2015-2088.html

Issue date: 2015-11-19

CVE Names: CVE-2015-5600 CVE-2015-6563 CVE-2015-6564

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

 

1. Summary:

 

Updated openssh packages that fix multiple security issues, several bugs,

and add various enhancements are now available for Red Hat Enterprise

Linux 7.

 

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.

 

2. Relevant releases/architectures:

 

Red Hat Enterprise Linux Client (v. 7) - x86_64

Red Hat Enterprise Linux Client Optional (v. 7) - x86_64

Red Hat Enterprise Linux ComputeNode (v. 7) - x86_64

Red Hat Enterprise Linux ComputeNode Optional (v. 7) - x86_64

Red Hat Enterprise Linux Server (v. 7) - aarch64, ppc64, ppc64le, s390x, x86_64

Red Hat Enterprise Linux Server Optional (v. 7) - aarch64, ppc64, ppc64le, s390x, x86_64

Red Hat Enterprise Linux Workstation (v. 7) - x86_64

Red Hat Enterprise Linux Workstation Optional (v. 7) - x86_64

 

3. Description:

 

OpenSSH is OpenBSD's SSH (Secure Shell) protocol implementation. These

packages include the core files necessary for both the OpenSSH client and

server.

 

A flaw was found in the way OpenSSH handled PAM authentication when using

privilege separation. An attacker with valid credentials on the system and

able to fully compromise a non-privileged pre-authentication process using

a different flaw could use this flaw to authenticate as other users.

(CVE-2015-6563)

 

A use-after-free flaw was found in OpenSSH. An attacker able to fully

compromise a non-privileged pre-authentication process using a different

flaw could possibly cause sshd to crash or execute arbitrary code with

root privileges. (CVE-2015-6564)

 

It was discovered that the OpenSSH sshd daemon did not check the list of

keyboard-interactive authentication methods for duplicates. A remote

attacker could use this flaw to bypass the MaxAuthTries limit, making it

easier to perform password guessing attacks. (CVE-2015-5600)

 

It was found that the OpenSSH ssh-agent, a program to hold private keys

used for public key authentication, was vulnerable to password guessing

attacks. An attacker able to connect to the agent could use this flaw to

conduct a brute-force attack to unlock keys in the ssh-agent. (BZ#1238238)

 

This update fixes the following bugs:

 

* Previously, the sshd_config(5) man page was misleading and could thus

confuse the user. This update improves the man page text to clearly

describe the AllowGroups feature. (BZ#1150007)

 

* The limit for the function for restricting the number of files listed

using the wildcard character (*) that prevents the Denial of Service (DoS)

for both server and client was previously set too low. Consequently, the

user reaching the limit was prevented from listing a directory with a large

number of files over Secure File Transfer Protocol (SFTP). This update

increases the aforementioned limit, thus fixing this bug. (BZ#1160377)

 

* When the ForceCommand option with a pseudoterminal was used and the

MaxSession option was set to "2", multiplexed SSH connections did not work

as expected. After the user attempted to open a second multiplexed

connection, the attempt failed if the first connection was still open. This

update modifies OpenSSH to issue only one audit message per session, and

the user is thus able to open two multiplexed connections in this

situation. (BZ#1199112)

 

* The ssh-copy-id utility failed if the account on the remote server did

not use an sh-like shell. Remote commands have been modified to run in an

sh-like shell, and ssh-copy-id now works also with non-sh-like shells.

(BZ#1201758)

 

* Due to a race condition between auditing messages and answers when using

ControlMaster multiplexing, one session in the shared connection randomly

and unexpectedly exited the connection. This update fixes the race

condition in the auditing code, and multiplexing connections now work as

expected even with a number of sessions created at once. (BZ#1240613)

 

In addition, this update adds the following enhancements:

 

* As not all Lightweight Directory Access Protocol (LDAP) servers possess

a default schema, as expected by the ssh-ldap-helper program, this update

provides the user with an ability to adjust the LDAP query to get public

keys from servers with a different schema, while the default functionality

stays untouched. (BZ#1201753)

 

* With this enhancement update, the administrator is able to set

permissions for files uploaded using Secure File Transfer Protocol (SFTP).

(BZ#1197989)

 

* This update provides the LDAP schema in LDAP Data Interchange Format

(LDIF) format as a complement to the old schema previously accepted

by OpenLDAP. (BZ#1184938)

 

* With this update, the user can selectively disable the Generic Security

Services API (GSSAPI) key exchange algorithms as any normal key exchange.

(BZ#1253062)

 

Users of openssh are advised to upgrade to these updated packages, which

correct these issues and add these enhancements.

 

4. Solution:

 

Before applying this update, make sure all previously released errata

relevant to your system have been applied.

 

For details on how to apply this update, refer to:

 

https://access.redhat.com/articles/11258

 

5. Bugs fixed (https://bugzilla.redhat.com/):

 

1125110 - pam_namespace usage is not consistent across system-wide PAM configuration

1160377 - sftp is failing using wildcards and many files

1178116 - Default selinux policy prevents ssh-ldap-helper from connecting to LDAP server

1181591 - No Documentation= line in the sshd.service file

1184938 - Provide LDIF version of LPK schema

1187597 - sshd -T does not show all (default) options, inconsistency

1197666 - ssh client using HostbasedAuthentication aborts in FIPS mode

1197989 - RFE: option to let openssh/sftp force the exact permissions on newly uploaded files

1238238 - openssh: weakness of agent locking (ssh-add -x) to password guessing

1245969 - CVE-2015-5600 openssh: MaxAuthTries limit bypass via duplicates in KbdInteractiveDevices

1252844 - CVE-2015-6563 openssh: Privilege separation weakness related to PAM support

1252852 - CVE-2015-6564 openssh: Use-after-free bug related to PAM support

 

6. Package List:

 

Red Hat Enterprise Linux Client (v. 7):

 

Source:

openssh-6.6.1p1-22.el7.src.rpm

 

x86_64:

openssh-6.6.1p1-22.el7.x86_64.rpm

openssh-askpass-6.6.1p1-22.el7.x86_64.rpm

openssh-clients-6.6.1p1-22.el7.x86_64.rpm

openssh-debuginfo-6.6.1p1-22.el7.x86_64.rpm

openssh-keycat-6.6.1p1-22.el7.x86_64.rpm

openssh-server-6.6.1p1-22.el7.x86_64.rpm

 

Red Hat Enterprise Linux Client Optional (v. 7):

 

x86_64:

openssh-debuginfo-6.6.1p1-22.el7.i686.rpm

openssh-debuginfo-6.6.1p1-22.el7.x86_64.rpm

openssh-ldap-6.6.1p1-22.el7.x86_64.rpm

openssh-server-sysvinit-6.6.1p1-22.el7.x86_64.rpm

pam_ssh_agent_auth-0.9.3-9.22.el7.i686.rpm

pam_ssh_agent_auth-0.9.3-9.22.el7.x86_64.rpm

 

Red Hat Enterprise Linux ComputeNode (v. 7):

 

Source:

openssh-6.6.1p1-22.el7.src.rpm

 

x86_64:

openssh-6.6.1p1-22.el7.x86_64.rpm

openssh-clients-6.6.1p1-22.el7.x86_64.rpm

openssh-debuginfo-6.6.1p1-22.el7.x86_64.rpm

openssh-keycat-6.6.1p1-22.el7.x86_64.rpm

openssh-server-6.6.1p1-22.el7.x86_64.rpm

 

Red Hat Enterprise Linux ComputeNode Optional (v. 7):

 

x86_64:

openssh-askpass-6.6.1p1-22.el7.x86_64.rpm

openssh-debuginfo-6.6.1p1-22.el7.i686.rpm

openssh-debuginfo-6.6.1p1-22.el7.x86_64.rpm

openssh-ldap-6.6.1p1-22.el7.x86_64.rpm

openssh-server-sysvinit-6.6.1p1-22.el7.x86_64.rpm

pam_ssh_agent_auth-0.9.3-9.22.el7.i686.rpm

pam_ssh_agent_auth-0.9.3-9.22.el7.x86_64.rpm

 

Red Hat Enterprise Linux Server (v. 7):

 

Source:

openssh-6.6.1p1-22.el7.src.rpm

 

aarch64:

openssh-6.6.1p1-22.el7.aarch64.rpm

openssh-clients-6.6.1p1-22.el7.aarch64.rpm

openssh-debuginfo-6.6.1p1-22.el7.aarch64.rpm

openssh-keycat-6.6.1p1-22.el7.aarch64.rpm

openssh-server-6.6.1p1-22.el7.aarch64.rpm

 

ppc64:

openssh-6.6.1p1-22.el7.ppc64.rpm

openssh-askpass-6.6.1p1-22.el7.ppc64.rpm

openssh-clients-6.6.1p1-22.el7.ppc64.rpm

openssh-debuginfo-6.6.1p1-22.el7.ppc64.rpm

openssh-keycat-6.6.1p1-22.el7.ppc64.rpm

openssh-server-6.6.1p1-22.el7.ppc64.rpm

 

ppc64le:

openssh-6.6.1p1-22.el7.ppc64le.rpm

openssh-askpass-6.6.1p1-22.el7.ppc64le.rpm

openssh-clients-6.6.1p1-22.el7.ppc64le.rpm

openssh-debuginfo-6.6.1p1-22.el7.ppc64le.rpm

openssh-keycat-6.6.1p1-22.el7.ppc64le.rpm

openssh-server-6.6.1p1-22.el7.ppc64le.rpm

 

s390x:

openssh-6.6.1p1-22.el7.s390x.rpm

openssh-askpass-6.6.1p1-22.el7.s390x.rpm

openssh-clients-6.6.1p1-22.el7.s390x.rpm

openssh-debuginfo-6.6.1p1-22.el7.s390x.rpm

openssh-keycat-6.6.1p1-22.el7.s390x.rpm

openssh-server-6.6.1p1-22.el7.s390x.rpm

 

x86_64:

openssh-6.6.1p1-22.el7.x86_64.rpm

openssh-askpass-6.6.1p1-22.el7.x86_64.rpm

openssh-clients-6.6.1p1-22.el7.x86_64.rpm

openssh-debuginfo-6.6.1p1-22.el7.x86_64.rpm

openssh-keycat-6.6.1p1-22.el7.x86_64.rpm

openssh-server-6.6.1p1-22.el7.x86_64.rpm

 

Red Hat Enterprise Linux Server Optional (v. 7):

 

aarch64:

openssh-askpass-6.6.1p1-22.el7.aarch64.rpm

openssh-debuginfo-6.6.1p1-22.el7.aarch64.rpm

openssh-ldap-6.6.1p1-22.el7.aarch64.rpm

openssh-server-sysvinit-6.6.1p1-22.el7.aarch64.rpm

pam_ssh_agent_auth-0.9.3-9.22.el7.aarch64.rpm

 

ppc64:

openssh-debuginfo-6.6.1p1-22.el7.ppc.rpm

openssh-debuginfo-6.6.1p1-22.el7.ppc64.rpm

openssh-ldap-6.6.1p1-22.el7.ppc64.rpm

openssh-server-sysvinit-6.6.1p1-22.el7.ppc64.rpm

pam_ssh_agent_auth-0.9.3-9.22.el7.ppc.rpm

pam_ssh_agent_auth-0.9.3-9.22.el7.ppc64.rpm

 

ppc64le:

openssh-debuginfo-6.6.1p1-22.el7.ppc64le.rpm

openssh-ldap-6.6.1p1-22.el7.ppc64le.rpm

openssh-server-sysvinit-6.6.1p1-22.el7.ppc64le.rpm

pam_ssh_agent_auth-0.9.3-9.22.el7.ppc64le.rpm

 

s390x:

openssh-debuginfo-6.6.1p1-22.el7.s390.rpm

openssh-debuginfo-6.6.1p1-22.el7.s390x.rpm

openssh-ldap-6.6.1p1-22.el7.s390x.rpm

openssh-server-sysvinit-6.6.1p1-22.el7.s390x.rpm

pam_ssh_agent_auth-0.9.3-9.22.el7.s390.rpm

pam_ssh_agent_auth-0.9.3-9.22.el7.s390x.rpm

 

x86_64:

openssh-debuginfo-6.6.1p1-22.el7.i686.rpm

openssh-debuginfo-6.6.1p1-22.el7.x86_64.rpm

openssh-ldap-6.6.1p1-22.el7.x86_64.rpm

openssh-server-sysvinit-6.6.1p1-22.el7.x86_64.rpm

pam_ssh_agent_auth-0.9.3-9.22.el7.i686.rpm

pam_ssh_agent_auth-0.9.3-9.22.el7.x86_64.rpm

 

Red Hat Enterprise Linux Workstation (v. 7):

 

Source:

openssh-6.6.1p1-22.el7.src.rpm

 

x86_64:

openssh-6.6.1p1-22.el7.x86_64.rpm

openssh-askpass-6.6.1p1-22.el7.x86_64.rpm

openssh-clients-6.6.1p1-22.el7.x86_64.rpm

openssh-debuginfo-6.6.1p1-22.el7.x86_64.rpm

openssh-keycat-6.6.1p1-22.el7.x86_64.rpm

openssh-server-6.6.1p1-22.el7.x86_64.rpm

 

Red Hat Enterprise Linux Workstation Optional (v. 7):

 

x86_64:

openssh-debuginfo-6.6.1p1-22.el7.i686.rpm

openssh-debuginfo-6.6.1p1-22.el7.x86_64.rpm

openssh-ldap-6.6.1p1-22.el7.x86_64.rpm

openssh-server-sysvinit-6.6.1p1-22.el7.x86_64.rpm

pam_ssh_agent_auth-0.9.3-9.22.el7.i686.rpm

pam_ssh_agent_auth-0.9.3-9.22.el7.x86_64.rpm

 

These packages are GPG signed by Red Hat for security. Our key and

details on how to verify the signature are available from

https://access.redhat.com/security/team/key/

 

7. References:

 

https://access.redhat.com/security/cve/CVE-2015-5600

https://access.redhat.com/security/cve/CVE-2015-6563

https://access.redhat.com/security/cve/CVE-2015-6564

https://access.redhat.com/security/updates/classification/#moderate

 

8. Contact:

 

The Red Hat security contact is . More contact

details at https://access.redhat.com/security/team/contact/

 

Copyright 2015 Red Hat, Inc.

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