What is a buffer overflow and how do I cause one?

Question

I have heard about a buffer overflow and I would like to know how to cause one.

Can someone show me a small buffer overflow example? New(And what they are used for?)

Answer 1

The "classic" buffer overflow example is:

int main(int argc, char *argv[])
{
    char buffer[10];
    strcpy(buffer, argv[1]);
}

That lets you play with the buffer overflow parameters and tweak them to your hearts content. The book "Hacking - The Art of Exploitation" (Link goes to Amazon) goes into great detail about how to play around with buffer overflows (purely as an intellectual exercise obviously).