SecureString theSecureString = new NetworkCredential("", "password").SecurePassword;


        Process installProcess = new Process();

        installProcess.StartInfo.UseShellExecute = false;
        installProcess.StartInfo.UserName = "admin";
        installProcess.StartInfo.Password = theSecureString;
        installProcess.StartInfo.FileName = @"installer.exe";


        installProcess.Start();