RHSA-2015:0439 - Security Advisory

Topic

Updated krb5 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.

Kerberos is a networked authentication system which allows clients and servers
to authenticate to each other with the help of a trusted third party, the
Kerberos KDC.

Description

A NULL pointer dereference flaw was found in the MIT Kerberos SPNEGO acceptor
for continuation tokens. A remote, unauthenticated attacker could use this flaw
to crash a GSSAPI-enabled server application. (CVE-2014-4344)

A buffer overflow was found in the KADM5 administration server (kadmind) when it
was used with an LDAP back end for the KDC database. A remote, authenticated
attacker could potentially use this flaw to execute arbitrary code on the system
running kadmind. (CVE-2014-4345)

A use-after-free flaw was found in the way the MIT Kerberos libgssapi_krb5
library processed valid context deletion tokens. An attacker able to make an
application using the GSS-API library (libgssapi) call the
gss_process_context_token() function could use this flaw to crash that
application. (CVE-2014-5352)

If kadmind were used with an LDAP back end for the KDC database, a remote,
authenticated attacker with the permissions to set the password policy could
crash kadmind by attempting to use a named ticket policy object as a password
policy for a principal. (CVE-2014-5353)

A double-free flaw was found in the way MIT Kerberos handled invalid External
Data Representation (XDR) data. An authenticated user could use this flaw to
crash the MIT Kerberos administration server (kadmind), or other applications
using Kerberos libraries, using specially crafted XDR packets. (CVE-2014-9421)

It was found that the MIT Kerberos administration server (kadmind) incorrectly
accepted certain authentication requests for two-component server principal
names. A remote attacker able to acquire a key with a particularly named
principal (such as "kad/x") could use this flaw to impersonate any user to
kadmind, and perform administrative actions as that user. (CVE-2014-9422)

An information disclosure flaw was found in the way MIT Kerberos RPCSEC_GSS
implementation (libgssrpc) handled certain requests. An attacker could send a
specially crafted request to an application using libgssrpc to disclose a
limited portion of uninitialized memory used by that application.
(CVE-2014-9423)

Two buffer over-read flaws were found in the way MIT Kerberos handled certain
requests. A remote, unauthenticated attacker able to inject packets into a
client or server application's GSSAPI session could use either of these flaws to
crash the application. (CVE-2014-4341, CVE-2014-4342)

A double-free flaw was found in the MIT Kerberos SPNEGO initiators. An attacker
able to spoof packets to appear as though they are from an GSSAPI acceptor could
use this flaw to crash a client application that uses MIT Kerberos.
(CVE-2014-4343)

Red Hat would like to thank the MIT Kerberos project for reporting the
CVE-2014-5352, CVE-2014-9421, CVE-2014-9422, and CVE-2014-9423 issues. MIT
Kerberos project acknowledges Nico Williams for helping with the analysis of
CVE-2014-5352.

The krb5 packages have been upgraded to upstream version 1.12, which provides a
number of bug fixes and enhancements, including:

• Added plug-in interfaces for principal-to-username mapping and verifying

authorization to user accounts.

• When communicating with a KDC over a connected TCP or HTTPS socket, the client

gives the KDC more time to reply before it transmits the request to another
server. (BZ#1049709, BZ#1127995)

This update also fixes multiple bugs, for example:

• The Kerberos client library did not recognize certain exit statuses that the

resolver libraries could return when looking up the addresses of servers
configured in the /etc/krb5.conf file or locating Kerberos servers using DNS
service location. The library could treat non-fatal return codes as fatal
errors. Now, the library interprets the specific return codes correctly.
(BZ#1084068, BZ#1109102)

In addition, this update adds various enhancements. Among others:

• Added support for contacting KDCs and kpasswd servers through HTTPS proxies

implementing the Kerberos KDC Proxy (KKDCP) protocol. (BZ#1109919)

Solution

All krb5 users are advised to upgrade to these updated packages, which correct
these issues and add these enhancements.

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

Affected Products

• Red Hat Enterprise Linux Server 7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.6 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.5 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.4 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.3 x86_64
• Red Hat Enterprise Linux Server - AUS 7.7 x86_64
• Red Hat Enterprise Linux Server - AUS 7.6 x86_64
• Red Hat Enterprise Linux Server - AUS 7.4 x86_64
• Red Hat Enterprise Linux Server - AUS 7.3 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 7 x86_64
• Red Hat Enterprise Linux Workstation 7 x86_64
• Red Hat Enterprise Linux Desktop 7 x86_64
• Red Hat Enterprise Linux for IBM z Systems 7 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.7 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.6 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.5 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.4 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.3 s390x
• Red Hat Enterprise Linux for Power, big endian 7 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.7 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.6 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.5 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.4 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.3 ppc64
• Red Hat Enterprise Linux for Scientific Computing 7 x86_64
• Red Hat Enterprise Linux Server from RHUI 7 x86_64
• Red Hat Enterprise Linux Server - TUS 7.7 x86_64
• Red Hat Enterprise Linux Server - TUS 7.6 x86_64
• Red Hat Enterprise Linux Server - TUS 7.3 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 7 s390x
• Red Hat Enterprise Linux EUS Compute Node 7.7 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.6 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.5 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.4 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.3 x86_64
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 7.7 x86_64
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 7.6 x86_64
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 7.4 x86_64
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 7.3 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support for IBM Power, big endian 7 ppc64

Fixes

• BZ - 1084068 - ipv6 address handling in krb5.conf
• BZ - 1102837 - Please backport improved GSSAPI mech configuration
• BZ - 1109102 - Kerberos does not handle incorrect Active Directory DNS SRV entries correctly
• BZ - 1109919 - Backport https support into libkrb5
• BZ - 1116180 - CVE-2014-4341 krb5: denial of service flaws when handling padding length longer than the plaintext
• BZ - 1118347 - ksu non-functional, gets invalid argument copying cred cache
• BZ - 1120581 - CVE-2014-4342 krb5: denial of service flaws when handling RFC 1964 tokens
• BZ - 1121789 - CVE-2014-4343: use-after-free crash in SPNEGO
• BZ - 1121876 - CVE-2014-4343 krb5: double-free flaw in SPNEGO initiators
• BZ - 1121877 - CVE-2014-4344 krb5: NULL pointer dereference flaw in SPNEGO acceptor for continuation tokens
• BZ - 1127995 - aggressive kinit timeout causes AS_REQ resent and subsequent OTP auth failure
• BZ - 1128157 - CVE-2014-4345 krb5: buffer overrun in kadmind with LDAP backend (MITKRB5-SA-2014-001)
• BZ - 1166012 - libkadmclnt SONAME change (8 to 9) in krb5 1.12 update
• BZ - 1174543 - CVE-2014-5353 krb5: NULL pointer dereference when using a ticket policy name as a password policy name
• BZ - 1179856 - CVE-2014-5352 krb5: gss_process_context_token() incorrectly frees context (MITKRB5-SA-2015-001)
• BZ - 1179857 - CVE-2014-9421 krb5: kadmind doubly frees partial deserialization results (MITKRB5-SA-2015-001)
• BZ - 1179861 - CVE-2014-9422 krb5: kadmind incorrectly validates server principal name (MITKRB5-SA-2015-001)
• BZ - 1179863 - CVE-2014-9423 krb5: libgssrpc server applications leak uninitialized bytes (MITKRB5-SA-2015-001)
• BZ - 1184629 - kinit loops on principals on unknown error

CVEs

• CVE-2014-4341
• CVE-2014-4344
• CVE-2014-4345
• CVE-2014-4343
• CVE-2014-4342
• CVE-2014-9421
• CVE-2014-9423
• CVE-2014-5353
• CVE-2014-5352
• CVE-2014-9422

References

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