Use scanf FSB to overwrite GOT and bypass ssp, then run ROP chian.
Use scanf again to set rax=SYS_execve and call execve system call.
[writeup](https://ptr-yudai.hatenablog.com/entry/2020/07/12/180442#Pwn-147pts-Beginners-Pwn-42-solves)

Original writeup (https://ptr-yudai.hatenablog.com/entry/2020/07/12/180442#Pwn-147pts-Beginners-Pwn-42-solves).