CTF Works

Tools and scripts for CTF exploit/pwnable challenge development.

Challenge Organization

• Each challenge goes in its own directory in challenges/${challenge}
• Each challenge must be packaged as a docker container and must have a Dockerfile
• Challenges can share binaries or any other file for distribution after packaging through /shared (if exists during runtime). Check start.sh in ppc32-simple-fmt challenge.
• Challenge meta data must go in challenges.json

Challenge developers must ensure that non-root privilege is obtained after exploiting target. Otherise the server/socat process will be killed by the attacker.

Currently we are using following socat command line to fork and execute as a different user:

$ socat -dd TCP4-LISTEN:9000,fork,reuseaddr EXEC:/pwnable,pty,setuid=bob,echo=0,raw,iexten=0

Flags

The flag for each challenge will be available from process environment variable. The name of the environment variable can be any of the following:

• FLAG
• PWNFLAG
• PFLAG
• FLAG-FOR-PWNS

Some challenges may still require flag to be in a file.

Development Environment

Create the virtual machine with Vagrant

$ vagrant up

Login with SSH and create ssh keys

$ vagrant ssh
$ ssh-keygen

The generated public need to be added to Bitbucket for repository access from inside the development environment. Do not forget to remove the keys from Bitbucket once development environment is no longer required.