Programs can also leave unused space after buffers, and keep an eye on those values to see if they change; if they do, they know an attacker is monkeying around with memory.

程序也可以在缓冲区后留一些不用的空间，然后跟踪里面的值，看是否发生变化，如果发生了变化，说明有攻击者在乱来。