Microsoft Security Bulletin MS99-050 - Important
Patch Available for "Server-side Page Reference Redirect" Vulnerability
Published: December 08, 1999
Originally Posted: December 08, 1999
Microsoft has released a patch that eliminates a vulnerability in Microsoft® Internet Explorer 4.01, 5 and 5.01, that could allow a malicious web site operator to view a file on the computer of a visiting user, provided that the web site operator knew the name and folder of the file.
Frequently asked questions regarding this vulnerability can be found at http://www.microsoft.com/technet/security/bulletin/fq99-050.mspx.
When a web server performs a server-side redirect, the IE security model checks the server's permissions on the new page. However, under favorable timing conditions, it is possible for a web server to create a reference to a client window that the server is permitted to view, then use a server-side redirect to a client-local file, and bypass the security restrictions. The result is that it could be possible for a malicious web site operator to view files on the computer of a visiting user. The web site operator would need to know (or guess) the name and location of the file.
Affected Software Versions
- Microsoft Internet Explorer 4.01
- Microsoft Internet Explorer 5.0
- Microsoft Internet Explorer 5.01
Vulnerability Identifier: CVE-1999-0981
NOTE: This patch also includes the previously-released patch for the "ImportExportFavorites" vulnerability.
NOTE: Microsoft produces security patches for Internet Explorer 4.01 SP2 and higher. In the event that this package is applied to Internet Explorer 4.01 SP1, the package states that a fix is not needed. This message is incorrect, as the vulnerability does exist on Internet Explorer 4.01 SP1 or any earlier release. If you are using Internet Explorer 4.01 SP1 or any earlier release, please upgrade to the latest version of Internet Explorer to resolve this issue.
NOTE: The patch will be available shortly at the WindowsUpdate site. When this happens, we will modify the bulletin to provide additional information.
Please see the following references for more information related to this issue.
- Microsoft Security Bulletin MS99-050: Frequently Asked Questions, http://www.microsoft.com/technet/security/bulletin/fq99-050.mspx.
- Microsoft Knowledge Base (KB) article 246094, Update Available for "Server-side Page Reference Redirect" Vulnerability, http://support.microsoft.com/default.aspx?scid=kb;en-us;246094&sd=tech.
(NOTE: It may take 24 hours from the original posting of this bulletin for this KB article to be visible.)
- Microsoft Security web site, http://www.microsoft.com/technet/security/default.mspx.
Obtaining Support on this Issue
This is a fully supported patch. Information on contacting Microsoft Technical Support is available at http://support.microsoft.com/contactussupport/?ws=support.
- December 08, 1999: Bulletin Created
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