File + Process Imports/Exports Information UDFs
Forwarder String Support, C++ Name Undecorating Added!!
(Extreme case of string forwarding from wsock32.dll example in this post)
This UDF gets Function Imports and Exports for any Windows PE file (.DLL, .EXE), both 32-bit and 64-bit (unlike most programs out there), and from either a 32-bit or 64-bit Process.
I created this due to my frustration with other programs either working only *some* of the time, or having a common inability to read PE32+ (x64) file format tables properly.
There's just two functions in the main UDF - _FileGetWinPEImports or _FileGetWinPEExports. The bundled TestImportExportsList program lets you explore files on your system.
*Newly included are: _ProcessGetWinPEImports, _ProcessGetWinPEExports and TestProcessImportExportsList program (requires my Process Functions UDF).
NOTE: *Compressed* executable files will only give the Import information for the 'decompressor'. The only way to get the compressed executable's Import information is to decompress the executable.
Anyway, enjoy my hard work. Either read on for more information about some of the features, or see below for the License agreement and Download link.
Information on 'Virtual Offset of Thunk':
These address offsets you see are offsets from the base of the .DLL or .EXE file (uncompressed only!), where the actual function location of an 'Import' gets placed. All calls to these functions load addresses from these Thunk locations in order to correctly place a call to the right DLL function. (This is totally different than the old Import fixup location lists of earlier pre-NT systems). Technically, you could overwrite these Thunks with addresses to your own functions, but this is a dangerous thing to do. Its a neat tool to have though.
Forwarder functions? An explanation:
The whole 'DLLNAME.Functionname' string might be confusing to you, but here's an explanation of why an address can not and should not be returned. To better understand all this, grab a copy of DLL Export Viewer, (which doesn't report Relative/Function addresses correctly for Forwarded functions) and then follow along: *update: as of v1.50, DLL Export Viewer now reports forwarder string info (I was the one that reported the bug heh)
Okay, open up DLL Export Viewer and look at (for this example) KERNEL32.DLL - lets pick 'HeapFree', a known Forwarded function. DLL Export Viewer reports the following (on XP SP3):Relative Address: 0x0000910c, 'Loaded' address: 0x7c80910c. *Neither* is the case, though - 0x0000910c is in fact just the virtual address of the forwarder string!
Now, with my Exports function, you'll find that 'HeapFree' is reported (correctly) as a Forwarder string. What you'll see then is 'NTDLL.RtlFreeHeap'. What does that mean? It means that:
- HeapFree is not a part of KERNEL32.DLL (and hasn't been for a while),
- When that function is called or the address retrieved via 'GetProcAddress', the function 'RtlFreeHeap' in NTDLL.DLL is the function that's actually called (or returned as an address). Hopefully the 'DLLNAME.FunctionName' structure of a Forwarder string is starting to make sense now?
- The address you get when you do 'GetProcAddress' does *not* correspond to what you see in DLL Export Viewer - in fact, 'HeapFree's reported address lies entirely OUTSIDE of kernel32.dll's memory space - pointing instead inside of NTDLL.DLL, at (guess what?): RtlFreeHeap.
So, there you have it in a nutshell - Forwarder functions are functions 'rerouted' to another DLL. The DLL's that are being rerouted to are either:
- A.) Pre-loaded by the system (Important DLL's like NTDLL.DLL, KERNEL32.DLL, USER32.DLL, GDI32.DLL, etc - are all permanently loaded)
- B.) Loaded upon a program's execution if the function is in its 'Imports' list, or
- C.) Loaded upon a call to GetProcAddress. To see how this works clearly, list the modules that are loaded (my Process Functions UDF GUI can do this for you), then call GetProcAddress for 'GetServiceW' from WSOCK32.DLL, and then re-list the modules again. You'll see a new module loaded up - MSWSOCK.DLL (the location of the forwarder function). Wa-la, forwarder is set up.
While I provide this source code freely, if you do use the code in your projects, all I ask is that:
- If you provide source, keep the header as I have put it, OR, if you expand it, then at least acknowledge me as the original author, and any other authors I credit
- If the program is released, acknowledge me in your credits (it doesn't have to state which functions came from me, though again if the source is provided - see #1)
- The source on it's own (as opposed to part of a project) can not be posted unless a link to the page(s) where the code were retrieved from is provided and a message stating that the latest updates will be available on the page(s) linked to.
- Pieces of the code can however be discussed on the threads where Ascend4nt has posted the code without worrying about further linking.
Edited by Ascend4nt, 26 September 2011 - 05:39 AM.