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Gentoo Linux Security Advisory                           GLSA 200803-31
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                                            http://security.gentoo.org/
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  Severity: High
     Title: MIT Kerberos 5: Multiple vulnerabilities
      Date: March 24, 2008
      Bugs: #199205, #212363
        ID: 200803-31

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Synopsis
========

Multiple vulnerabilites have been found in MIT Kerberos 5, which could
allow a remote unauthenticated user to execute arbitrary code with root
privileges.

Background
==========

MIT Kerberos 5 is a suite of applications that implement the Kerberos
network protocol. kadmind is the MIT Kerberos 5 administration daemon,
KDC is the Key Distribution Center.

Affected packages
=================

    -------------------------------------------------------------------
     Package             /  Vulnerable  /                   Unaffected
    -------------------------------------------------------------------
  1  app-crypt/mit-krb5     < 1.6.3-r1                     >= 1.6.3-r1

Description
===========

* Two vulnerabilities were found in the Kerberos 4 support in KDC: A
  global variable is not set for some incoming message types, leading
  to a NULL pointer dereference or a double free() (CVE-2008-0062) and
  unused portions of a buffer are not properly cleared when generating
  an error message, which results in stack content being contained in a
  reply (CVE-2008-0063).

* Jeff Altman (Secure Endpoints) discovered a buffer overflow in the
  RPC library server code, used in the kadmin server, caused when too
  many file descriptors are opened (CVE-2008-0947).

* Venustech AD-LAB discovered multiple vulnerabilities in the GSSAPI
  library: usage of a freed variable in the gss_indicate_mechs()
  function (CVE-2007-5901) and a double free() vulnerability in the
  gss_krb5int_make_seal_token_v3() function (CVE-2007-5971).

Impact
======

The first two vulnerabilities can be exploited by a remote
unauthenticated attacker to execute arbitrary code on the host running
krb5kdc, compromise the Kerberos key database or cause a Denial of
Service. These bugs can only be triggered when Kerberos 4 support is
enabled.

The RPC related vulnerability can be exploited by a remote
unauthenticated attacker to crash kadmind, and theoretically execute
arbitrary code with root privileges or cause database corruption. This
bug can only be triggered in configurations that allow large numbers of
open file descriptors in a process.

The GSSAPI vulnerabilities could be exploited by a remote attacker to
cause Denial of Service conditions or possibly execute arbitrary code.

Workaround
==========

Kerberos 4 support can be disabled via disabling the "krb4" USE flag
and recompiling the ebuild, or setting "v4_mode=none" in the
[kdcdefaults] section of /etc/krb5/kdc.conf. This will only work around
the KDC related vulnerabilities.

Resolution
==========

All MIT Kerberos 5 users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=app-crypt/mit-krb5-1.6.3-r1"

References
==========

  [ 1 ] CVE-2007-5901
        http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-5894
  [ 2 ] CVE-2007-5971
        http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-5971
  [ 3 ] CVE-2008-0062
        http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-0062
  [ 4 ] CVE-2008-0063
        http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-0063
  [ 5 ] CVE-2008-0947
        http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-0947

Availability
============

This GLSA and any updates to it are available for viewing at
the Gentoo Security Website:

  http://security.gentoo.org/glsa/glsa-200803-31.xml

Concerns?
=========

Security is a primary focus of Gentoo Linux and ensuring the
confidentiality and security of our users machines is of utmost
importance to us. Any security concerns should be addressed to
security@gentoo.org or alternatively, you may file a bug at
http://bugs.gentoo.org.

License
=======

Copyright 2008 Gentoo Foundation, Inc; referenced text
belongs to its owner(s).

The contents of this document are licensed under the
Creative Commons - Attribution / Share Alike license.

http://creativecommons.org/licenses/by-sa/2.5