MS02-049: Flaw Might Allow Web Page to Start Visual FoxPro 6.0 Application Without Warning (326568)

SYMPTOMS

During installation, a product generally registers itself with Internet Explorer. This allows the product to specify how Internet Explorer should handle files associated with it when referenced from a Web page. For example, with this registration process, the product can specify whether the user receives a warning before such a file is opened.

Visual FoxPro 6.0 does not perform this registration, and this creates a situation in which a Web page might automatically start a Visual FoxPro application (for example, an .app file). In most cases, this does not result in a security vulnerability. Because of the way that Visual FoxPro 6.0 evaluates file names, FoxPro itself might be started but the .app file would typically not run. However, if the file name of the application were constructed in a particular way, a second error (associated with how Visual FoxPro 6.0 evaluates application file names) might both start FoxPro and allow the application to run.

This vulnerability might be exploited by creating a Web page that references a Visual FoxPro application, and either hosting it on a Web site or sending it to a user as an .html file. If the user had installed Visual FoxPro 6.0 (or had installed a product that includes the Visual FoxPro 6.0 runtime), and the file name of the application was constructed in a particular way, the application would run. This would enable the application to not only interrogate databases, but also issue system commands in the user's security context.

RESOLUTION

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that this article describes. Apply it only to systems that you determine are at risk of attack. Evaluate the computer's physical accessibility, network and Internet connectivity, and other factors to determine the degree of risk to the computer. See the associated Microsoft Security Bulletin to help determine the degree of risk. This hotfix may receive additional testing. If the computer is sufficiently at risk, we recommend that you apply this hotfix now.

To resolve this problem immediately, download the hotfix by following the instructions later in this article or contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

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:

English (US): Download the Q326568 package now

Chinese (Simplified): Download the Q326568 package now

Chinese (Traditional): Download the Q326568 package now

Czech: Download the Q326568 package now

French: Download the Q326568 package now

German: Download the Q326568 package now

Korean: Download the Q326568 package now

Russian: Download the Q326568 package now

Spanish: Download the Q326568 package now

Release Date: September 4, 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:

119591 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 security-enhanced servers that help to prevent any unauthorized changes to the file.

Installation Options

You do not have to restart your computer after you apply this update. This update supports the following Setup switches:

/? Display the list of installation switches.
/Q Quiet mode.
/T:full path Specifies temporary working folder.
/C:Cmd Override Install Command defined by author.
/C Extract files only to the folder when used also with /T.

For example, the following command line installs the update without any user intervention:

vfp_q326568_en /q

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.

   Date         Time   Version        Size    Path
   -------------------------------------------------------
   06-Jun-2000  20:43  5.50.4134.600  92,432  Advpack.dll      
   25-Jul-2002  19:07                    881  Fpsf.inf
   06-Jun-2000  20:43  4.71.704.0      2,272  W95inf16.dll     
   06-Jun-2000  20:43  4.71.16.0       4,608  W95inf32.dll

NOTE: Because of file dependencies, this update may contain additional files.