Investigating a new win32hlp and Internet Explorer issue

Hi everyone,

On Friday 2/26/2010, an issue was posted publicly that could allow an attacker to host a maliciously crafted web page and run arbitrary code if they could convince a user to visit the web page and then get them to press the F1 key in response to a pop up dialog box. We are not aware of any attacks seeking to exploit this issue at this time and in the current state of our investigation, we have determined that users running Windows 7, Windows Server 2008 R2, Windows Server 2008, and Windows Vista, are not affected by this issue.

The issue in question involves the use of VBScript and Windows Help files in Internet Explorer. Windows Help files are included in a long list of what we refer to as “unsafe file types”. These are file types that are designed to invoke automatic actions during normal use of the files. While they can be very valuable productivity tools, they can also be used by attackers to try and compromise a system. To help customers better understand unsafe file types, we have published a white paper on the topic which you can find by clicking this link.

Once we have completed our investigation, we will take appropriate action to protect customers. To minimize risk to computer users, Microsoft continues to encourage responsible disclosure. Reporting vulnerabilities directly to vendors without further disclosure helps ensure that customers receive comprehensive, high-quality updates before cyber criminals learn of – and work to exploit – a vulnerability. Responsible disclosure protects the computer ecosystem and individual computer users from harm.

Anyone believed to have been affected can visit: and should contact the national law enforcement agency in their country.  Those in the United States can contact Customer Service and Support at no charge (for computer security related issues) using the PC Safety hotline at 1-866-727-2338 (PCSAFETY). Customers outside of the United States can visit to find local support information.

We continue to encourage customers to follow the “Protect Your Computer” guidance of enabling a firewall, applying all software updates and installing anti-virus and anti-spyware software. Additional information can be found at:

We will provide more information on this issue as it becomes available.


Jerry Bryant
Sr. Security Communications Manager Lead

*This posting is provided "AS IS" with no warranties, and confers no rights.*