Don't Press The F1 Key

Windows: pressing the F1 key might make your computer go boom. A security exploit deployed by certain malicious websites hides in the Windows help files and could get launched if you press the F1 button. It will only happen, if the following is true:

1. You’re using Windows 2000, XP, or 2003
2. You’re visiting a website using Internet Explorer
3. Website opens HTML help
4. Website runs a vbscript in said HTML help window that causes a message box prompt
5. You press F1 rather than clicking a button (like OK, cancel, etc) or closing the dialog

Microsoft’s statement:

Microsoft is investigating new public reports of a vulnerability in VBScript that is exposed on supported versions of Microsoft Windows 2000, Windows XP, and Windows Server 2003 through the use of Internet Explorer. Our investigation has shown that the vulnerability cannot be exploited on Windows 7, Windows Server 2008 R2, Windows Vista, or Windows Server 2008. The main impact of the vulnerability is remote code execution. We are not aware of attacks that try to use the reported vulnerabilities or of customer impact at this time.

The vulnerability exists in the way that VBScript interacts with Windows Help files when using Internet Explorer. If a malicious Web site displayed a specially crafted dialog box and a user pressed the F1 key, arbitrary code could be executed in the security context of the currently logged-on user. On systems running Windows Server 2003, Internet Explorer Enhanced Security Configuration is enabled by default, which helps to mitigate against this issue.

We are actively working with partners in our Microsoft Active Protections Program (MAPP) to provide information that they can use to provide broader protections to customers.

Upon completion of this investigation, Microsoft will take the appropriate action to help protect our customers. This may include providing a security update through our monthly release process or providing an out-of-cycle security update, depending on customer needs.

Microsoft is concerned that this new report of a vulnerability was not responsibly disclosed, potentially putting computer users at risk. We continue to encourage responsible disclosure of vulnerabilities. We believe the commonly accepted practice of reporting vulnerabilities directly to a vendor serves everyone’s best interests. This practice helps to ensure that customers receive comprehensive, high-quality updates for security vulnerabilities without exposure to malicious attackers while the update is being developed.

Don’t do it! Don’t press that F1 key! Noooooo.

Microsoft Security Advisory (981169) [Microsoft via Slashdot]

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