CTF Flag Submitter

Configuring for CTF

You can find an example competition file in competitions/mock.py, which you can use as a template for your own competitions/[competition name].py file.

Adding exploit scripts

The flag submitter handles concurrency and the flag submission, all that is needed is to place your exploit script in the scripts/ folder with the appropriate shebang line, and it'll be executed automatically in the format of ./script [team_id] [path to a file with json-encoded competition data, default /tmp/competition.json]. The script should print flags to stdout separated by a newline which will then be automatically submitted if the output hasn't ever been seen before and matches the flag format. Alternatively, you can also upload an entire folder and if it has exploit.py it'll be executed automatically instead.

Note that you don't need to ever restart the flag submitter process (unless the submission server dies), the scripts will be automatically detected.

Sample exploit script written in python:

#!/usr/bin/python3

import sys
import json
import time
import string
import random

team_id = sys.argv[1]
with open(sys.argv[2], 'r') as fin:
    competition = json.loads(fin.read())

time.sleep(2)

print('TEST_' + ''.join(random.choice(string.ascii_letters) for i in range(32)))

Running the project

You can install the project's dependencies with pip3 install -r requirements.txt. Then, to start up the project all you need to run is python3 ./main.py [competition name]. There are additionally optional flags --concurrent-teams-per-script, --script-timeout, and --statistics-delay that all take an integer value as input.

In some cases the project can exit, for example if the submission server was down. Due to this, it may make sense to set this up as a systemd service instead or monitor it actively that it still works.

To enable debug mode, you can have the magic DEBUG argument in argv.

For exploit development, you may want to use --dry-run flag and let this run in the background. It'll automatically keep up to date the /tmp/competition.json file so you don't need to hardcode any values each time they change, and ignore running the actual exploit scripts.

Status of the project

This project has been replaced with a private project instead, and only acts as a fallback if that project for some reason does not work and a workaround is needed immediately. As this project is designed to be very simple by design, it should continue working but any issues will most likely not be fixed (unless pull request is provided).