As the question says, I want to load a DLL from a location in memory instead of a file, similarly to LoadLibrary(Ex). I\'m no expert in WinAPI, so googled a little and found
Implementing your own DLL loader can get really hairy really fast. Reading this article it's easy to miss what kind of crazy edge cases you can get yourself into. I strongly recommend against it.
Just for a taste - consider you can't use any conventional debugging tools for the code in the DLL you're loading since the code you're executing is not listed in the region of any DLL known by the OS.
Another serious issue is dealing with DEP in windows.
Well, you can create a RAM Drive according to these instructions, then copy the DLL you can in memory to a file there and the use LoadLibrary().
Of course this is not very practical if you plan to deploy this as some kind of product because people are going to notice a driver being installed, a reboot after the installation and a new drive letter under My Computer. Also, this does nothing to actually hide the DLL since its just sitting there in the RAM Drive for everybody to watch.
Another thing I'm interested about is Why you actually want to do this? Perhaps your end result can be achieved by some other means other than Loading the DLL from memory. For instance when using a binary packer such as UPX, the DLL that you have on disk is different from the one that is eventually executed. Immediately after the DLL is loaded normally with LoadLibrary, The unpacker kicks in and rewrites the memory which the DLL is loaded to with the uncompressed binary (the DLL header makes sure that there is enough space allocated)