It's a heap exploitation challenge. Unlike traditional heap games, it is built on top of the latest musl-libc's mallocng heap.
In order to push players to learn and hack the new system, I tried to
simplify and mitigate the attack surface in the main binary. Players have
to exploit the free() in the internal heap implementaion to get a useful
memory corruption primitive.
In exploit.py I have provided a solution to gaining arbitrary memory write by leaking the context secret and crafting meta area.