Web proxy service may crash when it processes a redirect action

The Web proxy service (W3proxy.exe) may crash (that is, experience an access violation) when it processes an HTTP redirect action on a site and content rule that denies access.

ISA Server may not include the NULL terminating byte when ISA Server copies the redirect URL to a temporary buffer. Because of this, more HTTP header data may be sent back to the client in the redirect response, and sometimes the Web proxy service may crash.

You must install ISA Server Service Pack 1 (SP1) before you install the following hotfix. For more information about how to obtain the latest ISA Server service pack , click the following article number to view the article in the Microsoft Knowledge Base: A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language. The English version of this hotfix has the file attributes (or later file attributes) 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 item in Control Panel.This fix also applies to the French, German, Spanish, and Japanese versions of ISA Server.

To work around this problem, disable the URL redirect action on any site and content rule that denies access to a specific destination.

To disable a redirect action on a site and content rule, follow these steps:

1. In the ISA Server Microsoft Management Console (MMC), expand Servers and Arrays, and then expand the server name.
2. Expand Access Policy, and then click Site and Content Rules.
3. In the Action column, find all site and content rules that redirect to a URL. For example, the action may be "Redirect to: http://www.microsoft.com/isaserver".
4. In Advanced view, right-click a rule, and then click Properties .
5. On the Action tab, click to clear the If HTTP request, redirect request to this URL: check box.
6. Click OK to close the dialog box.

Repeat these steps for every rule that has a redirect action specified.

Note These steps apply to ISA Standard Edition. The steps for ISA Enterprise Edition may be a little different.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

To set up a site and content rule that denies access and that redirects the request, follow these steps:

1. In the ISA Server MMC, expand Servers and Arrays, and then expand the server name.
2. Expand Access Policy, and then click Site and Content Rules.
3. Create a site and content rule or select an existing rule that you want to configure. In Advanced view, right-click the rule, and then click Properties.
4. Click the Action tab, and then click to select the Denied and the If HTTP request, redirect request to this URL check boxes.
5. In the input that is listed below If HTTP request, redirect request to this URL, type the URL that you want to redirect to (for example, "Redirect to: http://www.microsoft.com/isaserver/").