Article ID: 2622172 - View products that this article applies to.
Important This article contains information that shows you how to help lower security settings or how to turn off security features on a computer. You can make these changes to work around a specific problem. Before you make these changes, we recommend that you evaluate the risks that are associated with implementing this procedure in your particular environment. If you implement this procedure, take any appropriate additional steps to help protect the computer.
Consider the following scenario:
In this scenario, ISA Server 2006 blocks access to the URL. Additionally, the ISA Web Proxy logs show a result code of 12232 for the denied request.
Note Keep in mind that this result code can also be logged because of other issues and that the URL that is logged would have to be reviewed for %0a or %0d characters to determine whether this is the issue that you experienced.
This problem occurs because the Forms Based Authentication filter blocks known cross-site scripting and related attacks. In this case, the filter is blocking response splitting attacks that also include carriage returns or linefeeds. However, valid URLs can also include these characters. For example, the IBM Rational Clearquest application is known to use carriage returns or linefeeds in its URLs.
To resolve this problem, install the ISA Server 2006 hotfix rollup package that is described in the following Microsoft Knowledge Base article:
(http://support.microsoft.com/kb/2616326/ )Description of the ISA Server 2006 hotfix package: September 2011
Warning This procedure may make a computer or a network more vulnerable to attack by malicious users or by malicious software such as viruses. We do not recommend this procedure but are providing this information so that you can implement this procedure at your own discretion. Use this procedure at your own risk.
The following script will disable the default behavior in ISA Server 2006 Service Pack 1 and enable the ISA Server to allow URLs that contain carriage returns (CR) or linefeeds (LF) in the URL address. To use this script, follow these steps.
ImportantNote Disabling this default behavior of ISA Server 2006 SP1 (in order to accommodate such applications) could also enable ISA Server to potentially allow the URLs that have been specifically crafted for “cross-site request forgery” attacks when ISA Server uses Form Based Authentication.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/824684/ )Description of the standard terminology that is used to describe Microsoft software updates
Article ID: 2622172 - Last Review: October 6, 2011 - Revision: 2.0
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