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  3. Microsoft ASP.NET AutoPostBack Variable Cross-Site Scripting Vulnerability

Microsoft ASP.NET AutoPostBack Variable Cross-Site Scripting Vulnerability

Risk

Medium

Date Discovered

October 10, 2006

Description

Microsoft ASP.NET is prone to a cross-site scripting vulnerability because the software fails to properly sanitize user-supplied input before it is rendered in the browser of an unsuspecting user in the context of the affected site. An attacker may leverage this issue to have arbitrary script code execute in the browser of an unsuspecting user, with the privileges of the victim user’s account. This may help the attacker steal cookie-based authentication credentials, retrieve sensitive information, and launch other attacks.

Technologies Affected

  • Microsoft .NET Framework 2.0
  • Microsoft Windows 2000 Server SP4
  • Microsoft Windows Server 2003 Datacenter Edition
  • Microsoft Windows Server 2003 Datacenter Edition SP1
  • Microsoft Windows Server 2003 Enterprise Edition
  • Microsoft Windows Server 2003 Enterprise Edition SP1
  • Microsoft Windows Server 2003 Standard Edition
  • Microsoft Windows Server 2003 Standard Edition SP1
  • Microsoft Windows Server 2003 Web Edition
  • Microsoft Windows Server 2003 Web Edition SP1
  • Microsoft Windows XP Home SP1
  • Microsoft Windows XP Home SP2
  • Microsoft Windows XP Media Center Edition
  • Microsoft Windows XP Media Center Edition SP1
  • Microsoft Windows XP Media Center Edition SP2
  • Microsoft Windows XP Professional SP1
  • Microsoft Windows XP Professional SP2
  • Microsoft Windows XP Professional x64 Edition
  • Microsoft Windows XP Tablet PC Edition

Recommendations

Block external access at the network boundary, unless external parties require service.

Filter access to the affected computer at the network boundary if global access isn't required. Restricting access to only trusted computers and networks might greatly reduce the likelihood of a successful exploit.

Run all software as a nonprivileged user with minimal access rights.

Attackers may successfully exploit client flaws in the browser through cross-site scripting vulnerabilities. When possible, run client software as regular user accounts with limited access to system resources. This may limit the immediate consequences of client-side vulnerabilities.

Do not follow links provided by unknown or untrusted sources.

Web users should be cautious about following links to sites that are provided by unfamiliar or suspicious sources. Filtering HTML from emails may help remove a possible vector for transmitting malicious links to users.

Set web browser security to disable the execution of script code or active content.

A successful exploit of cross-site scripting issues often requires executing malicious script code in web clients; consider disabling support for script code and active content within a client browser. Note that this mitigation tactic might adversely affect legitimate websites that rely on the execution of browser-based script code.
The vendor has released fixes to address this issue; please see the reference section for details.

Credits

Jaswinder Hayre discovered this vulnerability.
Copyright © Symantec Corporation.
Permission to redistribute this alert electronically is granted as long as it is not edited in any way unless authorized by Symantec Security Response. Reprinting the whole or part of this alert in any medium other than electronically requires permission from secure@symantec.com.

Disclaimer
The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.
Symantec, Symantec products, Symantec Security Response, and secure@symantec.com are registered trademarks of Symantec Corp. and/or affiliated companies in the United States and other countries. All other registered and unregistered trademarks represented in this document are the sole property of their respective companies/owners.

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