RemoveAllProxyAuthorization Not Applied to SSL Tunneling (CONNECT) Requests (810561)

IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

SYMPTOMS

If Internet Security and Acceleration (ISA) Server 2000 is chained to an upstream Web proxy server, you may receive incomplete HTML pages and random authentication prompts in the Web browser when you connect to secure HTTPS sites.

These symptoms may occur if the downstream ISA Server computer is configured to require Integrated proxy authentication and if the upstream Web proxy server is either configured to allow anonymous access or require proxy authentication (typically Basic proxy authentication). This problem occurs most frequently if you connect to a secure HTTPS site that uses a combination of HTTP and HTTPS links.

CAUSE

In certain circumstances, Web browsers may try to authenticate a connection with the downstream ISA Server computer that has already been authenticated with Integrated authentication. This may cause the downstream ISA Server computer to pass those credentials to the upstream Web proxy server. Because the credentials are for the downstream ISA Server computer and not for the upstream Web proxy server, the server returns a "407 Proxy authentication required" HTTP response. The downstream ISA Server computer then passes this HTTP response back to the Web browser, causing the authentication prompts on the client computer. Because the client cannot authenticate this request, incomplete HTML pages may result on the Web browser client.

This issue was resolved for outgoing HTTP requests in the following two ISA hotfixes, but not for outgoing HTTPS requests that use SSL tunneling. For additional information, click the following article numbers to view the articles in the Microsoft Knowledge Base:

317822 FIX: Problems with Web Browser if ISA Server 2000 Is Chained to an Upstream Web Proxy Server

297080 Incomplete HTML Pages and Random Authentication Prompts If ISA Server Is Chained to Upstream Proxy

RESOLUTION

You must install ISA Server Service Pack 1 (SP1) before you install the following hotfix. For additional informationabout how to obtain the latest ISA Server service pack, click the following article number to view the article in the Microsoft Knowledge Base:

313139 How to Obtain the Latest Internet Security and Acceleration Server 2000 Service Pack

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next service pack that contains this hotfix.

To resolve this problem immediately, 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:

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.

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     File name
   -------------------------------------------------------
   02-Apr-2003  17:04  3.0.1200.261  178,448  Mspadmin.exe     
   02-Apr-2003  17:04  3.0.1200.261  101,136  Msphlpr.dll         
   02-Apr-2003  17:03  3.0.1200.261  391,440  W3proxy.exe      
   02-Apr-2003  17:04  3.0.1200.261  298,768  Wspsrv.exe

This fix also applies to the French, German, Spanish, and Japanese versions of ISA Server.

MORE INFORMATION

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

To install the fix, run the self-extracting file. You do not have to restart the ISA Server computer. If the computer is part of an ISA Server array, you do not have to shut down the whole array. You can still install this fix on a one-by-one basis.

To implement the functionality in this fix, create one of the following registry keys: