D-Link hedwig.cgi - Cookie bof - return to system

This is the second exploit from the advisory by Roberto Paleari (http://www.exploit-db.com/exploits/27283/). As in the module https://github.com/rapid7/metasploit-framework/pull/3385 I have created a ROP to system and this starts the telnetd.

![dlink_hedwig_cgi_bof](https://cloud.githubusercontent.com/assets/497520/3132822/8bd5fca2-e813-11e3-8fd3-a081bf87f8b2.png)

This vulnerability is not only in the DIR-645. It is also in the firmware of the DIR300 and DIR600. I think there could be other devices out there that are also vulnerable.
jeah both are good but the default behaviour of the cmdstager echo module is changed, so all exploits using it should be checked too. Maybe there is a module that relies on the && but I don't think so.