Windows® via C/C++, Fifth Edition

Injecting a DLL with a Trojan DLL

Another way to inject a DLL is to replace a DLL that you know a process will load. For example, if you know that a process will load Xyz.dll, you can create your own DLL and give it the same filename. Of course, you must rename the original Xyz.dll to something else.

Inside your Xyz.dll, you must export all the same symbols that the original Xyz.dll exported. You can do this easily using function forwarders (described in Chapter 20), which make it trivially simple to hook certain functions, but you should avoid using this technique because it is not version-resilient. If you replace a system DLL, for example, and Microsoft adds new functions in the future, your DLL will not have function forwarders for them. Applications ...