[ GLSA 200405-07 ] Exim verify=header_syntax buffer overflow

From: Thierry Carrez (koon_at_gentoo.org)
Date: 05/14/04

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    Date: Fri, 14 May 2004 21:29:55 +0200
To: gentoo-announce@gentoo.org

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    Gentoo Linux Security Advisory GLSA 200405-07
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                                                http://security.gentoo.org/
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      Severity: High
         Title: Exim verify=header_syntax buffer overflow
          Date: May 14, 2004
          Bugs: #50217
            ID: 200405-07

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    Synopsis
    ========

    When the verify=header_syntax option is set, there is a buffer overflow
    in Exim that allows remote execution of arbitrary code.

    Background
    ==========

    Exim is an highly configurable message transfer agent (MTA) developed
    at the University of Cambridge.

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

        -------------------------------------------------------------------
         Package / Vulnerable / Unaffected
        -------------------------------------------------------------------
      1 net-mail/exim <= 4.33 >= 4.33-r1

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

    When the option "verify = header_syntax" is used in an ACL in the
    configuration file, Exim is vulnerable to a buffer overflow attack that
    can be triggered remotely by sending malicious headers in an email
    message. Note that this option is not enabled in Exim's default
    configuration file.

    Impact
    ======

    This vulnerability can be exploited to trigger a denial of service
    attack and potentially execute arbitrary code with the rights of the
    user used by the Exim daemon (by default this is the "mail" user in
    Gentoo Linux).

    Workaround
    ==========

    Make sure the verify=header_syntax option is not used in your exim.conf
    file.

    Resolution
    ==========

    All users of Exim should upgrade to the latest stable version:

        # emerge sync

        # emerge -pv ">=net-mail/exim-4.33-r1"
        # emerge ">=net-mail/exim-4.33-r1"

    References
    ==========

      [ 1 ] CAN-2004-0400
            http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-0400

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

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

         http://security.gentoo.org/glsa/glsa-200405-07.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 2004 Gentoo Technologies, 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/1.0

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