File Checker

pwn x86/x64 heap FCSC 2024 solved on

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Description

Between ACLs and LSMs, Unix permissions can no longer be trusted.

Here’s a program that tries to open a file of your choice to overcome this problem.

⚠️ libc must be stored on an ext4 filesystem, next to docker-compose.yml.

Files

  • docker-compose.yml
  • file-checker
    16.69 KiB – 53ef14680d0a90ce49223083c3d82727a9cf3660eb2e641835de610adf724d4a
  • file-checker-src.tar.xz
    845.49 KiB – 23cc8cfcb19bd9fb4c4829cafc035ec3c272cc9391d23561fc0a5c3de1f62a50
  • ld-2.39.so
    231.07 KiB – 555beffc7b3d2184dfd26c5446e4cbc89d0cdca63fa954bb38d77e574aa6b199
  • libc-2.39.so
    2.03 MiB – e4ed95c6c273277b9b8de5717ea272fef70cbe0e32053d6652e8a311b1f28f8d

Author

XeR

Challenge Instructions

  1. First, download docker-compose.yml:
    curl https://hackropole.fr/challenges/fcsc2024-pwn-file-checker/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.

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