[dfranke]

Windows suffers some famous dain bramage wrt to DLL loading paths: http://unhandledexpression.com/2010/08/23/fixing-the-dll-loa... Basically, even when "safe" DLL loading is turned on, the search path still includes the current directory. I'm guessing that Notepad and friends all look for some (legacy?) DLL that isn't always installed, so if an attacker puts a malicious DLL by its same name in the same path as the file being opened, it'll be loaded and executed. The part about network drives is probably just an assumption about trust boundaries: Microsoft assumes that attacker can't ordinarily put a malicious file in the same local folder that you're opening a text file in, but on a network drive anything goes.

This is all just speculation. I don't code for Windows, and I don't know anything more about this vulnerability than what's stated in the advisory.