In BSidesDelhi 2018 - data_bank challenge, there is a use after free (UAF) vulnerability which leads to tcache poisoning. Using this, we leak a libc address to de-randomize ASLR, and then put our fake chunk address into the tcache bin using tcache poisoning attack. As a result, we can force malloc to return our fake chunk before __malloc_hook, so we can overwrite __malloc_hook with one gadget. This is an interesting heap exploitation challenge to learn bypassing protections like NX, PIE, Canary, Full RELRO, and ASLR in x86_64 binaries in presence of tcache.