"Kinda like a poor man's instancer" - Delta
A minimalistic(ish) challenge instancer built on top of FastAPI, Docker and SSH.
Please remember that the studsec techstack for challenges looks something like this:
The instancer is responsible for starting and stopping challenge containers found in a challenge repo on some (ssh-connected) servers. The instancer acts very much like a control plane, starting and stopping VMs and setting up their ports.
The Instancer interacts with pwncrates through a webAPI defined in ./webapp/api.py. Additionally, this repo interacts with a challenge repo in the form of: Challenges using an API to be properly defined.
Firstly build the Docker container, this will only need to be done once.
docker-compose build
Next, place the required files/folders at the following locations:
challenges/ -> Challenge repository, crucially including a docker-compose.yml
keys/ -> SSH private key
Finally, you need to configure the instancer, the default settings are recommended. However, you will need to add the challenge servers
[servers.node1]
ip = "10.191.0.205"
port = "22"
user = "root"
path = "/srv"Here the ip value is mandatory, other fields can be specified on a per-server basis, if absent the value from
[servers.default] will be used.
Upon startup, the path directory will be cleared and populated with the challenge data.
a simple test has been added in ./test/test.py. In here every function prefixed with test will be treated as such. The tests can be executed with the following command when the container is running:
docker exec -it instancer /usr/local/bin/pytest ./test.pyFrom your challenge provider you'll want to interface with the instancer. For this the following API is provided:
/start/{user_id}/{service_name}
Takes an arbitrary user_id and a defined service_name and starts the challenge. The service_name is defined
in the challenge docker-compose.yml.
/stop/{user_id}/{service_name}
Takes an arbitrary user_id and a defined service_name and stops the challenge. The service_name is defined
in the challenge docker-compose.yml.
/status/{user_id}/{service_name}
Takes an arbitrary user_id and a defined service_name and returns the challenges status. The service_name is defined
in the challenge docker-compose.yml.