dc2020q - ooobash reversing

by reyammer

This was a jeopardy challenge, part of dc2020q. (CTFtime)

Points: 120
Was solved by: 58 teams
PCAPs: download

You may spawn the server:

On your laptop

Install docker
docker pull archiveooo/pub:ooobash (docker-saved download)
docker run -d --name ooobash archiveooo/pub:ooobash
Local IP: docker inspect ooobash -f '{{ .NetworkSettings.Networks.bridge.IPAddress }}'
Connect to that IP:5000 — Remember to docker rm -f when done.

On your laptop (full source)

Install docker and pip install PyYAML coloredlogs
git clone https://github.com/o-o-overflow/dc2020q-ooobash-public
cd ooobash
./spawner --log-level=INFO
Connect to the ip:port displayed

Hosted by OOO

Right now we're asking players to login first.

Description

Execute 'getflag' to get the flag.

Hints

None yet :(
If you wish, you can contribute some.

There's an author-recommended writeup.

Further (spoilery) pointers

An easier, unintended solution.

This challenge was actually created for the 2018 quals... fast forward to 2019, something happened in the bash world that opened an easy unintended solution.

Source

Spoilers ahead! Code for this challenge is publicly available.