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 TCP (6), UDP (17), or ALL (-1) protocols.

Rationale

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

Audit

From Console

Perform the following to determine if the account is configured as prescribed:

Log in to the AWS Management Console at https://console.aws.amazon.com/vpc/home.
In the left pane, click Network ACLs.
For each network ACL, perform the following:
- Select the network ACL.
- Click the Inbound Rules tab.
- Ensure no rule exists that has a port range that includes port 22, 3389, using the protocols TCP (6), UDP (17) or ALL (-1) or other remote server administration ports for your environment and has a Source of 0.0.0.0/0 and shows ALLOW.

Note: A Port value of ALL or a port range such as 0-1024 includes port 22, 3389, and other remote server administration ports.

Rationale​

Audit​

From Console​

References​

Rationale

Audit

From Console

References