RHSA-2004:236 - Security Advisory

Topic

Updated Kerberos 5 (krb5) packages which correct buffer overflows in the
krb5_aname_to_localname function are now available.

Description

Kerberos is a network authentication system.

Bugs have been fixed in the krb5_aname_to_localname library function.
Specifically, buffer overflows were possible for all Kerberos versions up
to and including 1.3.3. The krb5_aname_to_localname function translates a
Kerberos principal name to a local account name, typically a UNIX username.
This function is frequently used when performing authorization checks.

If configured with mappings from particular Kerberos principals to
particular UNIX user names, certain functions called by
krb5_aname_to_localname will not properly check the lengths of buffers
used to store portions of the principal name. If configured to map
principals to user names using rules, krb5_aname_to_localname would
consistently write one byte past the end of a buffer allocated from the
heap. The Common Vulnerabilities and Exposures project (cve.mitre.org) has
assigned the name CAN-2004-0523 to this issue.

Only configurations which enable the explicit mapping or rules-based
mapping functionality of krb5_aname_to_localname() are vulnerable.
These configurations are not the default.

Users of Kerberos are advised to upgrade to these erratum packages which
contain backported security patches to correct these issues.

Solution

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

To update all RPMs for your particular architecture, run:

rpm -Fvh [filenames]

where [filenames] is a list of the RPMs you wish to upgrade. Only those
RPMs which are currently installed will be updated. Those RPMs which are
not installed but included in the list will not be updated. Note that you
can also use wildcards (*.rpm) if your current directory *only* contains the
desired RPMs.

Please note that this update is also available via Red Hat Network. Many
people find this an easier way to apply updates. To use Red Hat Network,
launch the Red Hat Update Agent with the following command:

up2date

This will start an interactive process that will result in the appropriate
RPMs being upgraded on your system.

If up2date fails to connect to Red Hat Network due to SSL
Certificate Errors, you need to install a version of the
up2date client with an updated certificate. The latest version of
up2date is available from the Red Hat FTP site and may also be
downloaded directly from the RHN website:

https://rhn.redhat.com/help/latest-up2date.pxt

Affected Products

• Red Hat Enterprise Linux Server 3 x86_64
• Red Hat Enterprise Linux Server 3 ia64
• Red Hat Enterprise Linux Server 3 i386
• Red Hat Enterprise Linux Server 2 ia64
• Red Hat Enterprise Linux Server 2 i386
• Red Hat Enterprise Linux Workstation 3 x86_64
• Red Hat Enterprise Linux Workstation 3 ia64
• Red Hat Enterprise Linux Workstation 3 i386
• Red Hat Enterprise Linux Workstation 2 ia64
• Red Hat Enterprise Linux Workstation 2 i386
• Red Hat Enterprise Linux Desktop 3 x86_64
• Red Hat Enterprise Linux Desktop 3 i386
• Red Hat Enterprise Linux for IBM z Systems 3 s390x
• Red Hat Enterprise Linux for IBM z Systems 3 s390
• Red Hat Enterprise Linux for Power, big endian 3 ppc

Fixes

• BZ - 125001 - CAN-2004-0523 MIT Kerberos 5: buffer overflows in krb5_aname_to_localname

CVEs

• CVE-2004-0523

References

• http://web.mit.edu/kerberos/advisories/MITKRB5-SA-2004-001-an_to_ln.txt