Software Engineering Institute

The Microsoft .NET Framework is a managed code programming model for Microsoft Windows operating systems. Microsoft ASP.NET is a technology designed to allow programmers to create dynamic web sites and web applications.

A cross-site scripting vulnerability exists in the .NET Framework 2.0. This vulnerability occurs due to improper validation of HTTP request values.

An attacker may be able to obtain sensitive data from a user of a web site running a vulnerable version of the .NET Framework. Depending on the nature of the web site, this data may include passwords, credit card numbers, and any arbitrary information provided by the user. Likewise, information stored in cookies could be stolen or corrupted.

Update
Microsoft has released an update to address this issue. See Microsoft Security Bulletin MS06-056 for more details.

Workarounds for administrators

According to Microsoft, setting the AutoPostBack property to false may mitigate the affects of this vulnerability. See Microsoft Knowledgebase article 328923 for more information about the AutoPostBack property.

Workarounds for users

• Do not follow untrusted hyperlinks, especially if they are sent through email or instant messenger programs.
• Disable JavaScript. See the Securing your Web Browser document for instructions. Note that disabling JavaScript may reduce the functionality and features provided by some web sites.
• TypeURLs directly in the web browser's address bar, or use bookmarks to navigate to web sites.
• See the Cross-Site Scripting Vulnerabilities document for general information.