Можно ли на Python написать скрипт изменяющий данные в RAM конкретного запущенного приложения?
С помощью ctypes:
import sys
import ctypes
import ctypes.wintypes as wintypes


PROCESS_ALL_ACCESS = 0x1F0FFF

kernel32 = ctypes.windll.kernel32

kernel32.OpenProcess.restype = wintypes.HANDLE
kernel32.OpenProcess.argtypes = [
    wintypes.DWORD,
    wintypes.BOOL,
    wintypes.DWORD
]

kernel32.CloseHandle.restype = wintypes.BOOL
kernel32.CloseHandle.argtypes = [ wintypes.HANDLE ]

kernel32.WriteProcessMemory.restype = wintypes.BOOL
kernel32.WriteProcessMemory.argtypes = [ 
    wintypes.HANDLE,
    wintypes.LPVOID,
    wintypes.LPCVOID,
    ctypes.c_size_t,
    ctypes.POINTER(ctypes.c_size_t)
]


pid = int(sys.argv[1])
addr = int(sys.argv[2], 16)

val = 42
buf = (val).to_bytes(4, byteorder='little')
buf_ptr = ctypes.c_char_p(buf)

ph = kernel32.OpenProcess(PROCESS_ALL_ACCESS, False, pid)
kernel32.WriteProcessMemory(ph, addr, buf_ptr, len(buf), None)
kernel32.CloseHandle(ph)
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