Are you still using Windows XP? If so, be mindful of the F1 Button Exploit and how it attacks.

===[ ABSTRACT ]===============================================

It is possible to invoke winhlp32.exe from Internet Explorer 8,7,6
using VBScript. Passing malicious .HLP file to winhlp32 could allow
remote attacker to run arbitrary command.
Additionally, there is a stack overflow vulnerability in winhlp32.exe.

===[ AFFECTED SOFTWARE ]======================================

Windows XP SP3

NOT AFFECTED: Vista, Windows 7

===[ DESCRIPTION ]============================================

To trigger vulnerability some user interaction is needed. Victim has to
press F1 when MsgBox popup is displayed.

Syntax of MsgBox function:

MsgBox(prompt[,buttons][,title][,helpfile,context])

It is possible to pass remote samba share as helpfile parameter.
In addition there is a stack based buffer overflow when helpfile
parameter is too long. However, on XP winhlp32.exe is compiled with
/GS flag, which in this case effectively guard the stack.

Proof-of-Concept is available here:
http://isec.pl/poc-isec27/

===[ IMPACT ]=================================================

Score: MEDIUM

The vulnerability allows remote attacker to run arbitrary code on
victim machine.

===[ DISCLOSURE TIMELINE ]====================================

01 Feb 2007 The vulnerability was discovered.
26 Feb 2010 Public disclosure

===[ AUTHOR ]=================================================

Maurycy Prodeus | twitter.com/mprodeus

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Stephan Pringle

Technology Support Specialist at Sipylus

About The Author: Stephan Pringle is an Information Technology Support Specialist. He covers hardware and software and provides tips for you to troubleshoot and repair issues on your own. In his spare time, he writes articles about the State of New York on his Hackintosh and HackBook and that has helped him to become the top contributor of the New York City section of Yahoo! Answers.

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