[NT] Vulnerability in Compressed (zipped) Folders Allows Remote Code Execution (MS04-034)

From: SecuriTeam (support_at_securiteam.com)
Date: 10/13/04

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      Vulnerability in Compressed (zipped) Folders Allows Remote Code Execution
    (MS04-034)
    ------------------------------------------------------------------------

    SUMMARY

    A remote code execution vulnerability exists in Compressed (zipped)
    Folders because of an unchecked buffer in the way that it handles
    specially crafted compressed files. An attacker could exploit the
    vulnerability by constructing a malicious compressed file that could
    potentially allow remote code execution if a user visited a malicious Web
    site. An attacker who successfully exploited this vulnerability could take
    complete control of an affected system. However, user interaction is
    required to exploit this vulnerability.

    Note: Users whose accounts are configured to have fewer privileges on the
    system would be at less risk than users who operate with administrative
    privileges.

    DETAILS

    Vulnerable Systems:
     * Microsoft Windows XP and Microsoft Windows XP Service Pack 1 -
    <http://www.microsoft.com/downloads/details.aspx?FamilyId=6B70BA00-56D1-4314-8F53-F8355A6861D3> Download the update
     * Microsoft Windows XP 64-Bit Edition Service Pack 1 -
    <http://www.microsoft.com/downloads/details.aspx?FamilyId=3F6896F3-F055-438D-93CE-CD15F37264CB> Download the update
     * Microsoft Windows XP 64-Bit Edition Version 2003 -
    <http://www.microsoft.com/downloads/details.aspx?FamilyId=4B63EF24-D0E4-4005-8E23-2F5EC24BE63F> Download the update
     * Microsoft Windows Server 2003 -
    <http://www.microsoft.com/downloads/details.aspx?FamilyId=0903569E-7F3D-4846-A1DC-78734E77D3A9> Download the update
     * Microsoft Windows Server 2003 64-Bit Edition -
    <http://www.microsoft.com/downloads/details.aspx?FamilyId=4B63EF24-D0E4-4005-8E23-2F5EC24BE63F> Download the update

    Immune Systems:
     * Microsoft Windows NT Server 4.0 Service Pack 6a
     * Microsoft Windows NT Server 4.0 Terminal Server Edition Service Pack 6
     * Microsoft Windows 2000 Service Pack 3 and Microsoft Windows 2000
    Service Pack 4
     * Microsoft Windows XP Service Pack 2
     * Microsoft Windows 98, Microsoft Windows 98 Second Edition (SE), and
    Microsoft Windows Millennium Edition (Me)

    CVE Information:
     <http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-0575>
    CAN-2004-0575

    Mitigating Factors for Compressed (zipped) Folders Vulnerability
     * In a Web-based attack scenario, an attacker would have to host a Web
    site that contains a Web page that is used to exploit this vulnerability.
    An attacker would have no way to force users to visit a malicious Web
    site. Instead, an attacker would have to persuade them to visit the Web
    site, typically by getting them to click a link that takes them to the
    attacker's site.
     * An attacker who successfully exploited this vulnerability could gain
    the same privileges as the user. Users whose accounts are configured to
    have fewer privileges on the system would be at less risk than users who
    operate with administrative privileges.
     * By default, Outlook Express 6, Outlook 2002, and Outlook 2003 open HTML
    e-mail messages in the Restricted sites zone. Additionally, Outlook 98 and
    Outlook 2000 open HTML e-mail messages in the Restricted sites zone if the
     <http://go.microsoft.com/fwlink/?LinkId=33334> Outlook E-mail Security
    Update has been installed. Outlook Express 5.5 Service Pack 2 opens HTML
    e-mail in the Restricted sites zone if Microsoft Security Bulletin
    <http://go.microsoft.com/fwlink/?LinkId=19527> MS04-018 has been
    installed. The Restricted sites zone helps reduce attacks that could
    attempt to exploit this vulnerability.

    The risk of attack from the HTML e-mail vector can be significantly
    reduced if you meet all the following conditions:
       * Apply the update that is included with Microsoft Security Bulletin
    <http://go.microsoft.com/fwlink?linkid=19873> MS03-040 or a later
    Cumulative Security Update for Internet Explorer.
       * Use Internet Explorer 6 or later.
       * Use the Microsoft Outlook E-mail Security Update, use Microsoft
    Outlook Express 6 or later, or use Microsoft Outlook 2000 Service Pack 2
    or later in its default configuration.

    Workarounds for Compressed (zipped) Folders Vulnerability
     * Install <http://go.microsoft.com/fwlink/?LinkId=33334> Outlook E-mail
    Security Update if you are using Outlook 2000 SP1 or earlier, to help
    protect yourself from the HTML e-mail attack vector.
    By default, Outlook Express 6, Outlook 2002 and Outlook 2003 open HTML
    e-mail messages in the Restricted sites zone. Additionally, Outlook 98 and
    Outlook 2000 open HTML e-mail messages in the Restricted sites zone if the
     <http://go.microsoft.com/fwlink/?LinkId=33334> Outlook E-mail Security
    Update has been installed. Outlook Express 5.5 Service Pack 2 opens HTML
    e-mail in the Restricted sites zone if Microsoft Security Bulletin
    <http://go.microsoft.com/fwlink/?LinkId=19527> MS04-018 has been
    installed. The Restricted sites zone helps reduce attacks that could
    attempt to exploit this vulnerability.

     * Read e-mail messages in plain text format if you are using Outlook 2002
    or later, or Outlook Express 6 SP1 or later, to help protect yourself from
    the HTML e-mail attack vector.
    Microsoft Outlook 2002 users who have applied Office XP Service Pack 1 or
    later and Microsoft Outlook Express 6 users who have applied Internet
    Explorer 6 Service Pack 1 can enable this setting and view e-mail messages
    that are not digitally signed or e-mail messages that are not encrypted in
    plain text only.

    Digitally signed e-mail messages or encrypted e-mail messages are not
    affected by the setting and may be read in their original formats. For
    more information about enabling this setting in Outlook 2002, see
    Microsoft Knowledge Base Article
    <http://support.microsoft.com/default.aspx?scid=kb;en-us;307594> 307594.

    For information about this setting in Outlook Express 6, see Microsoft
    Knowledge Base Article <http://support.microsoft.com/?kbid=291387>
    291387.

    Impact of Workaround: E-mail messages that are viewed in plain text format
    will not contain pictures, specialized fonts, animations, or other rich
    content. In addition:
       * The changes are applied to the preview pane and to open messages.
       * Pictures become attachments so that they are not lost.
       * Because the message is still in Rich Text or HTML format in the
    store, the object model (custom code solutions) may behave unexpectedly.

     * Do not open or save .zip files that you receive from untrusted sources.
    This vulnerability could be exploited when a user views a .zip file. Do
    not open files that use this file name extension if the files are from
    untrusted sources. Administrators may want to consider restricting the use
    of .zip files as email attachments.

    FAQ for Compressed (zipped) Folders Vulnerability
    What is the scope of the vulnerability ?
    This is a remote code execution vulnerability. If a user is logged on with
    administrative privileges, an attacker who successfully exploited this
    vulnerability could take complete control of an affected system, including
    installing programs; viewing, changing, or deleting data; or creating new
    accounts with full privileges. Users whose accounts are configured to have
    fewer privileges on the system would be at less risk than users who
    operate with administrative privileges. However, user interaction is
    required to exploit this vulnerability.

    What causes the vulnerability ?
    An unchecked buffer in the way that Compressed (zipped) Folders processes
    specially crafted compressed files.

    What is Compressed (zipped) Folders ?
    The Compressed (zipped) Folders feature enables users to store data files
    and folders in a compressed (or zipped) format. Files and folders that are
    compressed require less space to store them. The feature lets users
    create, add files to, and extract files from zipped folders. For more
    information about Compressed (zipped) Folders, visit the following
    Microsoft
    <http://www.microsoft.com/windowsxp/home/using/productdoc/en/default.asp?url=/windowsxp/home/using/productdoc/en/vz_ovrvw.asp> Web site.

    Windows also offers another way to compress folders if your drive is
    formatted as NTFS,
    <http://support.microsoft.com/default.aspx?scid=kb;en-us;307987> NTFS file
    compression. However, NTFS file compression is significantly different
    from compressing files by using Compressed (zipped) Folders. To learn more
    about the similarities and differences between NTFS compression and
    Compressed (zipped) Folders, visit the following Microsoft
    <http://www.microsoft.com/windowsxp/home/using/productdoc/en/default.asp?url=/windowsxp/home/using/productdoc/en/ff_file_compress_overview.asp> Web site.

    What might an attacker use the vulnerability to do ?
    An attacker who successfully exploited this vulnerability could gain the
    same privileges as the user. Users whose accounts are configured to have
    fewer privileges on the system would be at less risk than users who
    operate with administrative privileges.

    How could an attacker exploit the vulnerability ?
    To exploit this vulnerability, an attacker could host a malicious Web site
    and then persuade a user to view that Web site. An attacker could also
    create an e-mail message that contains a specially crafted link, and then
    persuade a user to view the e-mail message and then click the link. An
    attacker could also send a specially crafted zipped file to a user and
    then persuade the user to open the file.

    An attacker could also access the affected component through another
    vector. For example, an attacker could log on to the system interactively
    or by using another program that passes parameters to the vulnerable
    component (locally or remotely).

    What systems are primarily at risk from the vulnerability ?
    Workstations and terminal servers are primarily at risk. Servers are only
    at risk if users who do not have sufficient administrative credentials are
    given the ability to log on to servers and to run programs. However, best
    practices strongly discourage allowing this.

    Could the vulnerability be exploited over the Internet ?
    Yes. An attacker may be able to exploit this vulnerability over the
    Internet.

    What does the update do ?
    The update removes the vulnerability by modifying the way that Compressed
    (zipped) Folders validates the length of a message before it passes the
    message to the allocated buffer.

    When this security bulletin was issued, had this vulnerability been
    publicly disclosed ?
    No. Microsoft received information about this vulnerability through
    responsible disclosure. Microsoft had not received any information
    indicating that this vulnerability had been publicly disclosed when this
    security bulletin was originally issued.

    When this security bulletin was issued, had Microsoft received any reports
    that this vulnerability was being exploited ?
    No. Microsoft had not received any information indicating that this
    vulnerability had been publicly used to attack customers and had not seen
    any examples of proof of concept code published when this security
    bulletin was originally issued.

    ADDITIONAL INFORMATION

    The information has been provided by Microsoft Product Security.
    The original article can be found at:
    <http://www.microsoft.com/technet/security/bulletin/MS04-034.mspx>
    http://www.microsoft.com/technet/security/bulletin/MS04-034.mspx

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