Hacker Ron Bowes has released various payloads that connect a shell’s standard input and output with a suitable online counterpart through DNS. This allows attackers to bypass many firewalls and even attack systems that have no internet connection themselves.
For a DNS tunnel, the host computer only needs to be able to resolve external host names such as http://www.h-online.com. It can then handle its network traffic via sent DNS queries and responses. This concept was already demonstrated by Julien Oster and Florian Heinz via the Name Server Transfer protocol (NSTX), which tunnels entire IP connections via DNS.
Ron Bowes has combined this with a command line shell for Linux and Windows, packaging the shell code in such a way that it can conveniently be integrated into exploits. He has even created a metasploit payload.
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Cobra Prey 