Microsoft Knowledge Base Article - Q329834
 

MS02-063: Unchecked Buffer in PPTP Implementation May Permit Denial-of-Service Attacks

The information in this article applies to:
  • Microsoft Windows XP Home Edition
  • Microsoft Windows XP Professional
  • Microsoft Windows XP 64-Bit Edition
  • Microsoft Windows 2000 Advanced Server
  • Microsoft Windows 2000 Professional
  • Microsoft Windows 2000 Server

SYMPTOMS

Windows 2000 and Windows XP have built-in support for Point-to-Point Tunneling Protocol (PPTP). This is a virtual private network (VPN) technology that is implemented as part of Remote Access Services. PPTP support is an optional component in Microsoft Windows NT 4.0, Microsoft Windows 98, Microsoft Windows 98 Second Edition, and Microsoft Windows Millennium Edition (Me).

There is a security vulnerability in the Windows 2000 and Windows XP implementations because of an unchecked buffer in a section of code that processes the control data that is used to establish, maintain, and remove PPTP connections. By delivering specially malformed PPTP control data to an affected server, an attacker might be able to corrupt kernel memory and cause the server to stop working, disrupting any work that is in progress on the server.

The vulnerability might be exploited against any server that offers PPTP. If a workstation is configured to operate as a remote access server that offers PPTP services, it can also be attacked. Workstations that act as PPTP clients can be attacked only during active PPTP sessions. Typical operation on an attacked computer can be restored by restarting the computer.

RESOLUTION

Windows XP

A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that you determine are at risk of attack. Evaluate your computer's physical accessibility, network and Internet connectivity, and other factors to determine the degree of risk to your computer. See the associated Microsoft Security Bulletin to help determine the degree of risk. This fix may receive additional testing. If your computer is sufficiently at risk, Microsoft recommends that you apply this fix now. Otherwise, wait for the next Windows XP service pack that contains this fix.

To resolve this problem immediately, download the fix by following the instructions later in this article or contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Download Information

The following files are available for download from the Microsoft Download Center:

Windows XP Professional and Windows XP Home EditionWindows XP 64-Bit EditionRelease Date: October 30, 2002

For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:
    Q119591 How to Obtain Microsoft Support Files from Online Services
Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on secure servers that prevent any unauthorized changes to the file.

Installation Information

You must restart your computer after you apply this update. This update supports the following Setup switches:
  • /? Display the list of installation switches.
  • /u Unattended mode.
  • /f Force other programs to quit when the computer shuts down.
  • /n Do not back up files for removal.
  • /o Overwrite OEM files without prompting.
  • /z Do not restart when installation is complete.
  • /q Quiet mode (no user interaction).
  • /l List installed hotfixes.
  • /x Extracts the files without running Setup.
For example, the following command line installs the update without any user intervention and then does not force the computer to restart:
    q329834_wxp_sp2_x86_enu /q /m /z
WARNING: Your computer is vulnerable until you restart it.

File Information

The English version of this fix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

The following files are installed in the %Windir%\System32\Drivers folder:

Windows XP Professional and Windows XP Home Edition
   Date         Time   Version        Size    File name
   ------------------------------------------------------------------
   01-Oct-2002  23:43  5.1.2600.101   46,208  Raspptp.sys  (pre-SP1)
   01-Oct-2002  22:52  5.1.2600.1129  46,208  Raspptp.sys  (with SP1)
Windows XP 64-Bit Edition
   Date         Time   Version        Size     File name
   -------------------------------------------------------------------
   01-Oct-2002  23:43  5.1.2600.101   165,888  Raspptp.sys  (pre-SP1)
   01-Oct-2002  22:52  5.1.2600.1128  166,528  Raspptp.sys  (with SP1)

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Windows 2000

A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that you determine are at risk of attack. Evaluate your computer's physical accessibility, network and Internet connectivity, and other factors to determine the degree of risk to your computer. See the associated Microsoft Security Bulletin to help determine the degree of risk. This fix may receive additional testing. If your computer is sufficiently at risk, Microsoft recommends that you apply this fix now. Otherwise, wait for the next Windows 2000 service pack that contains this fix.

To resolve this problem immediately, download the fix by following the instructions later in this article or contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Download Information

The following file is available for download from the Microsoft Download Center:
Release Date: October 30, 2002

For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:
    Q119591 How to Obtain Microsoft Support Files from Online Services
Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on secure servers that prevent any unauthorized changes to the file.

Installation Information

Because of file dependencies, this update requires Windows 2000 Service Pack 1 (SP1), Windows 2000 Service Pack 2 (SP2), or Service Pack 3 (SP3). For additional information, click the article number below to view the article in the Microsoft Knowledge Base:
    Q260910 How to Obtain the Latest Windows 2000 Service Pack
You must restart your computer after you apply this update. This update supports the following Setup switches:
  • /? Display the list of installation switches.
  • /u Unattended mode.
  • /f Force other programs to quit when the computer shuts down.
  • /n Do not back up files for removal.
  • /o Overwrite OEM files without prompting.
  • /z Do not restart when installation is complete.
  • /q Quiet mode (no user interaction).
  • /l List installed hotfixes.
  • /x Extracts the files without running Setup.
For example, the following command line installs the update without any user intervention and then does not force the computer to restart:
    q329834_w2k_sp4_x86_en /q /m /z
WARNING: Your computer is vulnerable until you restart it.

File Information

The English version of this fix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

The following file is installed in the %Windir%\System32\Drivers folder: 
   Date         Time   Version        Size    File name
   ------------------------------------------------------
   01-Oct-2002  21:55  5.0.2195.6076  46,640  Raspptp.sys

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