Rating:

The binary has a Format String Bug.
We can overwrite the GOT addrees of `perror` and `printf` in order to get the shell.

[writeup](https://ptr-yudai.hatenablog.com/entry/2019/03/25/152043#Pwn-998pts-Simple)

Original writeup (https://ptr-yudai.hatenablog.com/entry/2019/03/25/152043#Pwn-998pts-Simple).