Issue

Permissions 0777 for 'your_key.pem' are too open.
It is required that your private key files are NOT accessible by others.

Solution

https://rainbound.tistory.com/entry/%EC%9C%88%EB%8F%84%EC%9A%B0-ssh-%EC%97%B0%EA%B2%B0-%EC%97%90%EB%9F%ACpermissions-too-open%EB%93%B1