RHSA-2009:0408 - Security Advisory

Topic

Updated krb5 packages that fix various security issues are now available
for Red Hat Enterprise Linux 5.

This update has been rated as having important security impact by the Red
Hat Security Response Team.

Description

Kerberos is a network authentication system which allows clients and
servers to authenticate to each other using symmetric encryption and a
trusted third party, the Key Distribution Center (KDC). The Generic
Security Service Application Program Interface (GSS-API) definition
provides security services to callers (protocols) in a generic fashion. The
Simple and Protected GSS-API Negotiation (SPNEGO) mechanism is used by
GSS-API peers to choose from a common set of security mechanisms.

An input validation flaw was found in the ASN.1 (Abstract Syntax Notation
One) decoder used by MIT Kerberos. A remote attacker could use this flaw to
crash a network service using the MIT Kerberos library, such as kadmind or
krb5kdc, by causing it to dereference or free an uninitialized pointer.
(CVE-2009-0846)

Multiple input validation flaws were found in the MIT Kerberos GSS-API
library's implementation of the SPNEGO mechanism. A remote attacker could
use these flaws to crash any network service utilizing the MIT Kerberos
GSS-API library to authenticate users or, possibly, leak portions of the
service's memory. (CVE-2009-0844, CVE-2009-0845)

All krb5 users should upgrade to these updated packages, which contain
backported patches to correct these issues. All running services using the
MIT Kerberos libraries must be restarted for the update to take effect.

Solution

Before applying this update, make sure that all previously-released
errata relevant to your system have been applied.

This update is available via Red Hat Network. Details on how to use
the Red Hat Network to apply this update are available at
http://kbase.redhat.com/faq/docs/DOC-11259

Affected Products

• Red Hat Enterprise Linux Server 5 x86_64
• Red Hat Enterprise Linux Server 5 ia64
• Red Hat Enterprise Linux Server 5 i386
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 5.3 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 5.3 ia64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 5.3 i386
• Red Hat Enterprise Linux Workstation 5 x86_64
• Red Hat Enterprise Linux Workstation 5 i386
• Red Hat Enterprise Linux Desktop 5 i386
• Red Hat Enterprise Linux for IBM z Systems 5 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 5.3 s390x
• Red Hat Enterprise Linux for Power, big endian 5 ppc
• Red Hat Enterprise Linux Server from RHUI 5 x86_64
• Red Hat Enterprise Linux Server from RHUI 5 i386
• Red Hat Enterprise Linux Server - AUS 5.3 x86_64
• Red Hat Enterprise Linux Server - AUS 5.3 ia64
• Red Hat Enterprise Linux Server - AUS 5.3 i386
• Red Hat Enterprise Linux Desktop 5 x86_64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 5.3 ppc

Fixes

• BZ - 490634 - CVE-2009-0845 krb5: NULL pointer dereference in GSSAPI SPNEGO (MITKRB5-SA-2009-001)
• BZ - 491033 - CVE-2009-0844 krb5: buffer over-read in SPNEGO GSS-API mechanism (MITKRB5-SA-2009-001)
• BZ - 491036 - CVE-2009-0846 krb5: ASN.1 decoder can free uninitialized pointer when decoding an invalid encoding (MITKRB5-SA-2009-002)

CVEs

• CVE-2009-0846
• CVE-2009-0844
• CVE-2009-0845

References

• http://www.redhat.com/security/updates/classification/#important
• http://web.mit.edu/kerberos/advisories/MITKRB5-SA-2009-001.txt
• http://web.mit.edu/kerberos/advisories/MITKRB5-SA-2009-002.txt