Control: 18 Security groups should only allow unrestricted incoming traffic for authorized ports

Description

This control checks whether the security groups that are in use allow unrestricted incoming traffic. Optionally the rule checks whether the port numbers are listed in the authorizedTcpPorts parameter.

• If the security group rule port number allows unrestricted incoming traffic, but the port number is specified in authorizedTcpPorts, then the control passes. The default value for authorizedTcpPorts is 80, 443.
• If the security group rule port number allows unrestricted incoming traffic, but the port number is not specified in authorizedTcpPorts input parameter, then the control fails.
• If the parameter is not used, then the control fails for any security group that has an unrestricted inbound rule.

Security groups provide stateful filtering of ingress and egress network traffic to AWS. Security group rules should follow the principal of least privileged access. Unrestricted access (IP address with a /0 suffix) increases the opportunity for malicious activity such as hacking, denial-of-service attacks, and loss of data.

Remediation

For information on how to modify a security group, see Add, remove, or update rules.