Process Hook and Read From Memory VB6

• needs spellchecked

To learn how to hook a running program in Windows we will use calc.exe, the windows calculator, as a guinea pig. So, we create a Visual BASIC program that attaches itself to calc.exe and monitors for the calculator value to change from zero.

Already found four key addresses to use for testing with a debugger:

calc.exe+14D55          01014D55
calc.exe+14D56          01014D56
calc.exe+14D57          01014D57
calc.exe+14D58          01014D58

1. Get the Process ID of calc.exe
2. Hook the Process
3. Read the Memory

• Getwindowthreadprocessid

• ReadProcessMemory: Reads data from an area of memory in a specified process. The entire area to be read must be accessible or the operation fails.

BOOL ReadProcessMemory(
  HANDLE hProcess,
  LPCVOID lpBaseAddress,
  LPVOID lpBuffer,
  SIZE_T nSize,
  SIZE_T* lpNumberOfBytesRead
);

ReadProcessMemory hProcess [in], lpBaseAddress [in], lpBuffer[out], nSize[in], lpNumberOfBytesRead[out]

If the function succeeds, the return value is nonzero. If the function fails, the return value is 0 (zero).

The GetWindowThreadProcessId function retrieves the identifier of the thread that created the specified window and, optionally, the identifier of the process that created the window.