Check your EC2 security groups for inbound rules that allow unrestricted access (i.e. 0.0.0.0/0 or ::/0) to TCP port 22. Restrict access to only those IP addresses that require it, in order to implement the principle of least privilege and reduce the possibility of a breach. TCP port 22 is used for secure remote login by connecting an SSH client application with an SSH server: https://en.wikipedia.org/wiki/Secure_Shell
Allowing unrestricted SSH access can increase opportunities for malicious activity such as hacking, man-in-the-middle attacks (MITM) and brute-force attacks.
To determine if your EC2 security groups allow unrestricted SSH access, perform the following:
To update your security groups inbound/ingress configuration in order to restrict SSH access to specific entities (IP addresses, IP ranges, etc), perform the following: