On Sat, Mar 26, 2016 at 12:07 AM, Matt Breedlove
<[email protected]> wrote:
> Somehow, that clarification doesn't do much to improve my clarity.

Top-poster! Well, there's a distinct chance I completely misunderstood
it. If it means the memory of the process then I'm completely off the
mark, and it it would seem like a pretty dumb exploit vector if it
weren't limited to a single processes memory too.

>
> On Fri, Mar 25, 2016 at 7:49 PM, Ray Donnelly <[email protected]> wrote:
>> On Fri, Mar 25, 2016 at 11:34 PM, Óscar Fuentes <[email protected]> wrote:
>>> Matt Breedlove <[email protected]>
>>> writes:
>>>
>>>> DLLs load from the system32/wow64 directory first *regardless* of any
>>>> PATH variables.  This was a prior problem I experienced with python
>>>> being built and there having been openssl dlls within my system
>>>> directories.  It has nothing to do with the path variable.  This is
>>>> documented behavior on MSDN and requires a system call to change the
>>>> search paths.  Ray is correct, although I typically use procmon from
>>>> the SysInternals Microsoft suite and just filter for dll paths.  If
>>>> you have a dll with the same name as the one a process is trying to
>>>> load within system32/SysWOW64, it will override any dlls that might be
>>>> present within PATH.
>>>>
>>>> Here's the URL that describes the behavior:
>>>>
>>>> https://msdn.microsoft.com/en-us/library/7d83bc18.aspx
>>>>
>>>> Because his zlib.dll file for msys2 doesn't reside in the same
>>>> directory that conftest.exe is being compiled in, Windows will search
>>>> the system directories first and then progress along the PATH
>>>> directories.  This is unless a specific call is made to change that
>>>> behavior (which it is not).
>>>
>>> My point was that Ray's comment could be interpreted as saying that
>>> having *any* foo.dll on your system and a process that uses it implies
>>> that you will have problems if your application comes with its own
>>> foo.dll.
>>>
>>> If you place your foo.dll along the rest of the binaries of your
>>> application, you are safe, no matter how many other foo.dlls you have
>>> around on your system.
>>>
>>> I'm sure that Ray knows this, but as the discussion progressed some
>>> context was lost and on the final messages it is not obvious that the
>>> problem is related to relying on PATH for locating zlib.dll and having
>>> other zlib.dll on the Windows system directory.
>>>
>>> There is much confussion with dlls on Windows and I've met many
>>> programmers who hold the weirdest ideas about it (as demonstrated by the
>>> other response to your message.)
>>>
>>
>> Hi Óscar,
>>
>> From MSDN:
>>
>> https://msdn.microsoft.com/en-us/library/windows/desktop/ms682586(v=vs.85).aspx
>>
>> "If a DLL with the same module name is already loaded in memory, the
>> system checks only for redirection and a manifest before resolving to
>> the loaded DLL, no matter which directory it is in. The system does
>> not search for the DLL."
>>
>>>
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