The System Security research group (S2G) at NTNU have organized semi-weekly CTF competitions with a different main focus each time (web, mobile, osint, forensics etc.). I will create writeups for some of the more interesting challenges, and the ones I learned the most from.

Read more at ntnu.edu

Challenges:

  • Sleepy (rev medium)

    • Patching libc_sleep to speed up a binary

    S2G rev Sleepy challenge

    Patching an ELF with exponential sleeping, to run faster and print the flag.

  • Pickle Postcards (web easy)

    • Basic python pickle challenge

    S2G web Pickle Postcards

    Exploiting pythons _reduce_ to create a payload that when loaded on the server gives us a reverse shell.

  • Simplerop (pwn hard)

    • Double sigreturn to call execve("/bin/sh")

    S2G pwn Simplerop

    Pwning a small binary with sigreturn and multiple syscalls.