Malicious script can use LD_PRELOAD or similar mechanisms to run any command given permission to run some specific command and 'write' permission with any valid path.

https://gist.github.com/GoldsteinE/5a51b105c23e6bbc3f06346bc47a336f
https://asciinema.org/a/zldYPwkLGlRoH4mPvNQ0IPQhX