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Used to write data to a remote process. Malware uses WriteProcessMemory as part of process injection.


BOOL WINAPI WriteProcessMemory(
  _In_   HANDLE hProcess,
  _In_   LPVOID lpBaseAddress,
  _In_   LPCVOID lpBuffer,
  _In_   SIZE_T nSize,
  _Out_  SIZE_T *lpNumberOfBytesWritten


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 process.
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.