WriteProcessMemory()

Writes data to an area of memory in a specified process. The entire area to be written to must be accessible or the operation fail.

Syntax

C++

BOOL WINAPI WriteProcessMemory(

_In_    HANDLE    hProcess,

_In_    LPVOID     lpBaseAddress,

_In_    LPCVOID   lpBuffer,

_In_    SIZE_T      nSize,

_Out_   SIZE_T     *lpNumberOfBytesWritten    

);

Parameters

hProcess[in]

A handle to the process memory to be modified. The handle must have PROCESS_VM_WRITE and PROCESS_VM_OPERATION access to the process.

lpBaseAddress[in]

A pointer to the base address in the specified process to which data is written. Before data transfer occurs, the system verifies that all data in the base address and memory of the specified size is accessible for write access, and if it is not accessible, the function fails.

lpBuffer [in]

A pointer to the buffer that contains data to be written in the address space of the specified pross

nSize[in]

The number of bytes to be written to the specified process.

lpNumberOfBytesWritten[out]

A pointer to a variable that receives the number of bytes transferred into the specified process. This parameter is optional. If lpNumberOfBytesWritten is NULL, the parameter is ignored.

Return value

If the function succeeds, the return value is nonzero

If the function fails, the return value is 0 (zero). To get extended error information, call GetLastError. The function fails if the requested write operation crosses into an area of the process that is inaccessible.

Remarks

WriteProcessMemory copies the data from the specified buffer in the current process to the address range of the specified process. Any process that has a handle with PROCESS_VM_WRITE and PROCESS_VM_OPERATION access to the process to be written to can call the function. Typically but not always, the process with address space that is being written to is being debugged.

The entire area to be written to must be accessible, and if it is not accessible, the function fails.

Requirements 

Header    WinBase.h (including Windows.h)

Library    Kernel32.lib

DLL       Kernel32.dll

See also 

Debugging Functions

Process Functions for Debugging

ReadProcessMemory

VirtualAllocEx