CreateRemoteThread failing with ERROR_ACCESS_DENIED

Question

I'm trying to learn the basics of dll injection, so I created a really simple hello-world type DLL and an injector based off of code I found online. I wasn't able to find anything that works out of the box, so I had to make a few adjustments.

Injection Code, DLL Code

I'm running these on 64-bit windows. I'm compiling with Visual Studio 2010. The injector is a win32 console app, and the dll is win32 as well. I'm trying to inject my code into an existing notepad process (also 32-bit). All of this is running on Windows 7 x64.

When I run the injector, it fails every time at CreateRemoteThread, with GetLastError returning 5 (i.e. ERROR_ACCESS_DENIED). I've confirmed that the dll path is correct (although changing it to a bogus path gives the same behavior), and I've confirmed that the path is getting written to notepad's memory at the correct address using Cheat Engine. I'm having a difficult time with this because I'm not sure how to debug the problem further.

What could be causing CreateRemoteThread to fail?

Answer 1

The problem is that notepad.exe is a 64-bit process in 64-bit windows, and I was trying to inject with a 32-bit process.

Answer 2

I also come up with the same problem. My situation is this:

1. My system is 64-bit and the notepad is also 64-bit.

2. But the injector is the 32-bit process.

My solution is to replace the 64-bit notepad with the 32-bit notepad in the system directory.