VBScript in Microsoft Windows 2000 SP4, XP SP2 and SP3, and Server 2003 SP2, when Internet Explorer is used, allows user-assisted remote attackers to execute arbitrary code by referencing a (1) local pathname, (2) UNC share pathname, or (3) WebDAV server with a crafted .hlp file in the fourth argument (aka helpfile argument) to the MsgBox function, leading to code execution involving winhlp32.exe when the F1 key is pressed.