In `MeePwn 2018 - BabySandbox` challenge, lesson learned is that `openat`, `readv`, and `writev` syscalls are the alternatives for `open`, `read`, and `write` syscalls, respectively, when the latter syscalls are blocked.

Original writeup (https://github.com/sajjadium/ctf-writeups/tree/master/MeePwn/2018/BabySandbox).