Reduce the possibility of a breach by checking EC2 security groups for inbound rules that allow unfettered access to TCP port 445, commonly used by client/server applications, and restrict access to IP addresses that require this port.
Rationale
Malicious activity, such as denial-of-service (DoS) or man-in-the-middle attacks (MITM), can occur when permitting unrestricted Common Internet File System (CIFS) access. TCP port 445 is the port commonly used by client/server applications as a means of communication between network nodes over TCP.
Remediation
From the console
Follow the Security group rules docs to learn how to add a security group rule that will restrict access to IP addresses that require a specific port.
From the command line
Run revoke-security-group-ingress to remove inbound rules that allow unrestricted access to port 445.
