DNS port - 53 is used to query Domain Names to IP address. Allowing inbound traffic from all external IP addresses to DNS port can be vulnerable to DNS Hijacking, Cache Poisoning, DNS Tunnelling attack. It is a best practice to restrict access from known public DNS server to destination port 53.
Recommended Mitigation
It is recommended to replace the source IP of the rule with a specific IP address or delete the rule.
Network misconfigurations
