RPG

pwn x86/x64 FCSC 2022 solved on

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Description

Jean-Michel is a huge fan of tabletop RPG. Unfortunately, his friends and him have been unable to play ever since the COVID-19 outbreak began.

They worked on a simple chat client that lets players roll all sorts of dices using a CSPRNG.

Here is the first version of their software. Find a vulnerability and read the flag.

Files

  • docker-compose.yml
  • ld-2.33.so
    211.12 KiB – 7dc3322b6cceb01e2a8a24667f254ffd8202ae2a6636809456c054c313904239
  • libc-2.33.so
    1.89 MiB – 86ca990a4719b1d4ed8f56e9c6c373e33ad8a40a85fb262cc9ac94ab67feaed0
  • Makefile
    188 B – dd7e5d6fb0a7cd5f614d33a91855ea52acc70a43806480a8aeb93ba2f34fd801
  • rpg
    16.65 KiB – e8a2ead8cc72d1e133f1226d2aff5ec0cdd9d78917d0d3a830c0c6c459a91b14
  • rpg.c
    2.95 KiB – 9708500ba07fc28be2061f41adfbdbad2e6815539ad9aecaa3f464ef2465a6bb

Author

XeR

Challenge Instructions

  1. First, download docker-compose.yml:
    curl https://hackropole.fr/challenges/fcsc2022-pwn-rpg/docker-compose.public.yml -o docker-compose.yml
  2. Launch the challenge by executing in the same folder:
    docker compose up
  3. Then, in another console, access the challenge with Netcat:
    nc localhost 4000
⚠️ Important: You must solve the challenge by interacting with the Docker container through the exposed network port. Any other way is not considered valid.

In case you encounter problems, please consult the FAQ.

Flag

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Writeups

There are no public solutions for this challenge yet, but you can submit yours after getting the flag.