Control: 5.1 Ensure no Network ACLs allow ingress from 0.0.0.0/0 to remote server administration ports

Description

The Network Access Control List (NACL) function provide stateless filtering of ingress and egress network traffic to AWS resources. It is recommended that no NACL allows unrestricted ingress access to remote server administration ports, such as SSH to port 22 and RDP to port 3389, using either the TCP (6), UDP (17) or ALL (-1) protocols.

Public access to remote server administration ports, such as 22 and 3389, increases resource attack surface and unnecessarily raises the risk of resource compromise.

Remediation

From Console:

Perform the following:

1. Log into the AWS Management Console at https://console.aws.amazon.com/vpc/home.
2. In the left pane, click Network ACLs.
3. For each network ACL to remediate, perform the following:
   • Select the network ACL.
   • Click the Inbound Rules tab.
   • Click Edit inbound rules.
   • Either A) update the Source field to a range other than 0.0.0.0/0, or, B) Click Delete to remove the offending inbound rule.
   • Click Save.