Outbound access on all ports should be restricted

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Description

Reduce the probability of a breach by checking EC2 security groups for outbound rules that allow unfettered access to any TCP/UDP ports and restrict access to IP addresses that require this port.

Rationale

Malicious activity, such as denial-of-service (DoS) and distributed denial-of-service (DDoS) attacks, can occur when permitting unfettered outbound access.

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

  1. Run revoke-security-group-egress to remove IP permissions for the selected EC2 security group.

    revoke-security-group-egress.sh

        aws ec2 revoke-security-group-egress
            --group-id your-group-id
            --ip-permissions '[{"IpProtocol": "tcp", "FromPort": 22, "ToPort": 22, "IpRanges": [{"CidrIp": "0.0.0.0/0"}]}]'
        
  2. Run authorize-security-group-egress with new parameters to restrict outbound access to specific destinations.

    authorize-security-group-egress.sh

        aws ec2 authorize-security-group-egress
            --group-id your-group-id
            --ip-permissions '[{"IpProtocol": "tcp", "FromPort": 22, "ToPort": 22, "IpRanges": [{"CidrIp": "0.0.0.0/0"}]}]'