• Article

Security Bulletin

Microsoft Security Bulletin MS99-022 - Important

Patch Available for "Double Byte Code Page" Vulnerability

Published: June 24, 1999 | Updated: March 10, 2003

Version: 2.0

Patch Availability Information Updated: March 10, 2003

Originally Posted: June 24, 1999

IIS 4.0 Patch Re-released: August 19, 1999

Summary

Microsoft has released a patch that eliminates a vulnerability in Microsoft® Internet Information Server that could allow a web site visitor to view the source code for selected files on the server, if the server's default language is set to Chinese, Japanese or Korean.

This patch originally was released on June 24, 1999. However, the IIS 4.0 version of the patch was found to contain a regression error. The regression error has been eliminated and the new patch is now available.

Frequently asked questions regarding this vulnerability can be found at https://www.microsoft.com/technet/security/bulletin/fq99-022.mspx

Issue

When IIS is run on a machine on which a double-byte character set code page is used (i.e., the default language on the server is set to Chinese, Japanese, or Korean), and a specific URL construction is used to request a file in a virtual directory, normal server-side processing is bypassed. As a result, the file is simply delivered as text to the browser, thereby allowing the source code to be viewed.

Affected Software Versions

  • Microsoft Internet Information Server 3.0 and 4.0, if run on a server whose default language is set to Chinese, Korean, or Japanese

Vulnerability Identifier: CVE-1999-0725

Patch Availability

  • English: https:

  • Simplified Chinese: </https:>https:

  • Traditional Chinese: </https:>https:

  • Japanese: </https:>https:

  • Korean: </https:>https:

    Note   Apply the patch corresponding to the language version of IIS, rather than the current default language on the server. For example, if you have the English version of IIS but have reset the default language on the server to Chinese, apply the English patch.

More Information

Please see the following references for more information related to this issue.

  • Microsoft Security Bulletin MS99-022: Frequently Asked Questions, https://www.microsoft.com/technet/security/bulletin/MS99-022faq.mspx.

  • Microsoft Knowledge Base (KB) article 233335, Page Contents Visible When Certain Characters are at End of URL, </https:>https:.

    (Note It may take 24 hours from the original posting of this bulletin for the KB article to be visible; however, a copy will be immediately available in the patch folder.)

  • Microsoft Security web site, </https:>https:.

  • IIS Security Checklist, </https:>https:.

Obtaining Support on this Issue

This is a fully supported patch. Information on contacting Microsoft Technical Support is available at </https:>https:.

Revisions

  • June 24, 1999: Bulletin Created.
  • August 19, 1999: IIS 4.0 Patch re-released
  • V2.0 (March 10, 2003): Introduced versioning and updated patch availability information

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