/UIUCTF-2023-Public

Challenge source code, official writeups, and infrastructure setup for UIUCTF 2023

Primary LanguageC

UIUCTF-2023-Public

Note
This is the repository for all UIUCTF 2023 challenges and infrastructure. This is an exact copy of our development repository, minus some deployment secrets and git history.

Flag format: uiuctf{...}

For Challenge Devs: Adding a Challenge

  • Do you need a container?

    • YES:
      • cd into /challenges/<category>
      • kctf chal create --template <templatename> <chalname> --challenge-dir ./<chalname>
      • Available templates: pwn, web, xss-bot
      • Note: the kCTF config is challenge.yaml and the CTFd config is challenge.yml. Confusing? Yes.
    • NO
      • mkdir /challenges/<category>/<chalname>

  • Your challenge folder MUST have a challenge.yml file for CTFd, following the specification here

  • Your challenge must have a healthcheck script if it is deployable - attempt to make it solve the challenge

  • Your challenge should have a SOLUTION.md writeup (it's ok if it's simple/concise or a TL;DR version)

For Challenge Devs: Local Development for Containerized Challenges

Initial setup

  • Follow kCTF setup instructions here
    • umask a+x
    • Install dependencies (CLI tools, Docker)
    • Enable user namespaces:
      • `echo 'kernel.unprivileged_userns_clone=1' | sudo tee -a /etc/sysctl.d/00-local-userns.conf
      • sudo service procps restart
  • Helpful: export DOCKER_SCAN_SUGGEST=false - disables annoying Snyk messages from newer Docker versions which break kCTF parsing

After initial setup

Every time you open a new shell, you will need to do the following:

  • cd to root of this repository
  • source kctf/activate

Testing locally

  • Switch to and start local cluster:
    • kctf cluster load local-cluster
    • kctf cluster start
  • Start challenge and port forward to access it:
    • kctf chal start
    • kctf chal debug port-forward
  • When done testing:
    • kctf cluster stop to shutdown local k8s cluster
      • Do NOT run this command on remote-cluster or you will delete the Google Cloud cluster
    • deactivate to exit ctfcli

Testing deployed challenge on remote cluster

  • Push to repo, and run the kCTF GitHub action
  • Switch to remote cluster:
    • kctf cluster load remote-cluster
  • Port forward to access it:
    • kctf chal debug port-forward
  • When done testing:
    • deactivate to exit ctfcli

For Infrastructure Admins: Setting Up Google Cloud

These instructions only need to be done once before the CTF.

Prerequisites

Set up Kubernetes

Create cluster:

kctf cluster create --project dotted-forest-314903 --domain-name chal.uiuc.tf --start --email-address sigpwny@gmail.com --zone us-central1-a --registry us.gcr.io remote-cluster --disable-src-ranges

Note: --disable-src-ranges disables Cloud Armor. To remove, you need the SECURITY_POLICIES quota.

Resize cluster (to reduce costs before CTF starts):

kctf cluster resize --min-nodes 1 --max-nodes 1 --num-nodes 1 --machine-type e2-standard-4 --pool-name default-pool --spot

Test challenge deployment

cd to a challenge folder with a deployment challenge.yaml file and run the following:

kctf chal start

Set up CTFd

Enable services

You may need to enable SQL and Redis services. Run the following commands. If you see a prompt like API [sqladmin.googleapis.com] not enabled on project [648434879266]. Would you like to enable and retry (this will take a few minutes)? (y/N)?, press y.

gcloud sql instances list
gcloud redis instances list --region us-central1

Setup script

Run from the root directory:

./ctfd/chal setup

Setting up CI/CD

GitHub Actions needs some secrets to automatically sync with the CTFd instance. After creating a CTFd admin account, go to http:///settings#tokens to obtain a token.

From the root of the repository, create the .ctf/config file with the new IP and token. Note that you need git-crypt to unlock and edit the file. These credentials will be automatically used by the GitHub Actions workflow to connect to CTFd and sync/install challenges.