Control: 5.2 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 provides 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 on port 22 and RDP on port 3389, using either the TCP (6), UDP (17), or ALL (-1) protocols.

Public access to remote server administration ports, such as 22 (when used for SSH, not SFTP) and 3389, increases the attack surface of resources and unnecessarily raises the risk of resource compromise.

Remediation

From Console:

Perform the following steps to remediate a network ACL:

1. Login to the AWS VPC Console at https://console.aws.amazon.com/vpc/home.
2. In the left pane, click Network ACLs.
3. For each network ACL that needs remediation, 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.