Add these methods:
[DllImport("kernel32.dll")]
static extern IntPtr OpenProcess(ProcessAccessFlags dwDesiredAccess, [MarshalAs(UnmanagedType.Bool)] bool bInheritHandle, int dwProcessId);
[DllImport("kernel32.dll", SetLastError = true)]
static extern bool WriteProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, byte[] lpBuffer, uint nSize, out int lpNumberOfBytesWritten);
[DllImport("kernel32.dll")]
public static extern Int32 CloseHandle(IntPtr hProcess);
Flags:
[Flags]
public enum ProcessAccessFlags : uint
{
All = 0x001F0FFF,
Terminate = 0x00000001,
CreateThread = 0x00000002,
VMOperation = 0x00000008,
VMRead = 0x00000010,
VMWrite = 0x00000020,
DupHandle = 0x00000040,
SetInformation = 0x00000200,
QueryInformation = 0x00000400,
Synchronize = 0x00100000
}
With this I can implement a method to simplify:
public static void WriteMem(Process p, IntPtr address, long v)
{
var hProc = OpenProcess(ProcessAccessFlags.All, false, (int)p.Id);
var val = new byte[] { (byte)v };
int wtf = 0;
WriteProcessMemory(hProc, address, val, (UInt32)val.LongLength, out wtf);
CloseHandle(hProc);
}
In this way I can use:
static void Main(string[] args)
{
var p = Process.GetProcessesByName("ePSXe").FirstOrDefault();
WriteMem(p, new IntPtr(0x00A66DB9), 99);
}
References in English: