How to replace (hook) a Windows function with a custom one using MS Detours?

1 year ago

Comment

1 / 1

To replace (hook) a Windows function with a custom one using MS Detours, you can follow these steps:

Download and install the MS Detours library from the official Microsoft Research website: https://github.com/Microsoft/Detours
Include the necessary Detours headers in your C++ code:
```
cpp
#include <detours.h>
```
Define a function with the same signature as the target function you want to hook. This will be your custom function that will replace the original function. Make sure to use the same calling convention (e.g., __stdcall, __cdecl) as the original function.
```
cpp
// Custom function to replace the target function

// Use the same signature as the target function

int MyTargetFunction(int arg1, int arg2) {

    // Your custom implementation here

    // ...

}
```
Before the program execution reaches the point where the target function is called, use the DetourTransactionBegin() and DetourUpdateThread() functions to begin the transaction and update the thread state.
```
cpp
DetourTransactionBegin();

DetourUpdateThread(GetCurrentThread());
```
Use the DetourAttach() function to attach your custom function to the target function.
```
cpp
DetourAttach(&(PVOID&)OriginalTargetFunction, MyTargetFunction);
```
Finalize the transaction using the DetourTransactionCommit() function.
```
cpp
DetourTransactionCommit();
```
Now, when the target function is called, it will be redirected to your custom function.

Keep in mind that hooking Windows functions using MS Detours involves low-level manipulation and should be done carefully. Make sure to handle error cases, clean up properly, and ensure compatibility with the target function's calling convention and behavior.

It's also worth noting that MS Detours is a research project and not officially supported by Microsoft. Therefore, it's recommended to thoroughly test your code and consider alternative hooking libraries or techniques based on your specific requirements.