RHSA-2015:0794 - Security Advisory

Topic

Updated krb5 packages that fix multiple security issues 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.

Description

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.

The following security issues are fixed with this release:

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) could call the
gss_process_context_token() function and 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 who has 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)

It was found that the krb5_read_message() function of MIT Kerberos did not
correctly sanitize input, and could create invalid krb5_data objects.
A remote, unauthenticated attacker could use this flaw to crash a Kerberos
child process via a specially crafted request. (CVE-2014-5355)

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, via 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)

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

All krb5 users are advised to upgrade to these updated packages, which
contain backported patches to correct these issues.

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

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.6 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.6 i386
• Red Hat Enterprise Linux Server - AUS 6.6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.6 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.6 ppc64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 i386
• Red Hat Enterprise Linux Server - TUS 6.6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.6 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.6 i386
• Red Hat Enterprise Linux EUS Compute Node 6.6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension (for IBM z Systems) 6 s390x

Fixes

• 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 - 1193939 - CVE-2014-5355 krb5: unauthenticated denial of service in recvauth_common() and others

CVEs

• CVE-2014-9421
• CVE-2014-5353
• CVE-2014-5352
• CVE-2014-9422
• CVE-2014-5355

References

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