For AI agents: A markdown version of this page is available at https://docs.datadoghq.com/security/code_security/iac_security/iac_rules/cloudformation-aws-gamelift-fleet-ec2-inbound-permissions-with-port-range.md. A documentation index is available at /llms.txt.

GameLift fleet EC2 inbound permissions with port range

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Metadata

Id: cloudformation-aws-gamelift-fleet-ec2-inbound-permissions-with-port-range

Provider: AWS

Platform: CloudFormation

Severity: Medium

Category: Networking and Firewall

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Description

Opening port ranges for GameLift fleet instances increases the attack surface by exposing multiple ports instead of a single intended port. This can allow additional network-based attacks and makes it harder to reason about allowed traffic.

For AWS::GameLift::Fleet resources, each entry in the Properties.EC2InboundPermissions array must set FromPort and ToPort to the same numeric value so only a single port is opened. Resources with EC2InboundPermissions entries where FromPort is not equal to ToPort will be flagged. Ensure both properties are defined and equal for every entry.

Secure configuration example:

MyGameLiftFleet:
  Type: AWS::GameLift::Fleet
  Properties:
    EC2InboundPermissions:
      - FromPort: 3478
        ToPort: 3478
        IpRange: 0.0.0.0/0
        Protocol: UDP

Compliant Code Examples

Resources:
  FleetResource2:
    Type: AWS::GameLift::Fleet
    Properties:
      BuildId: !Ref BuildResource
      CertificateConfiguration:
        CertificateType: DISABLED
      Description: Description of my Game Fleet
      DesiredEc2Instances: 1
      EC2InboundPermissions:
        - FromPort: '1234'
          ToPort: '1234'
          IpRange: 0.0.0.0/24
          Protocol: TCP
        - FromPort: '1356'
          ToPort: '1356'
          IpRange: 192.168.0.0/24
          Protocol: UDP

{
  "Resources": {
    "FleetResource2": {
      "Type": "AWS::GameLift::Fleet",
      "Properties": {
        "CertificateConfiguration": {
          "CertificateType": "DISABLED"
        },
        "Description": "Description of my Game Fleet",
        "DesiredEc2Instances": 1,
        "EC2InboundPermissions": [
          {
            "FromPort": "1234",
            "ToPort": "1234",
            "IpRange": "0.0.0.0/24",
            "Protocol": "TCP"
          },
          {
            "ToPort": "1356",
            "IpRange": "192.168.0.0/24",
            "Protocol": "UDP",
            "FromPort": "1356"
          }
        ],
        "BuildId": "BuildResource"
      }
    }
  }
}

Non-Compliant Code Examples

Resources:
  FleetResource1:
    Type: AWS::GameLift::Fleet
    Properties:
      BuildId: !Ref BuildResource
      CertificateConfiguration:
        CertificateType: DISABLED
      Description: Description of my Game Fleet1
      DesiredEc2Instances: 1
      EC2InboundPermissions:
        - FromPort: '1234'
          ToPort: '134'
          IpRange: 0.0.0.0/24
          Protocol: TCP
        - FromPort: 1356
          ToPort: 1578
          IpRange: 192.168.0.0/24
          Protocol: UDP
  FleetResource3:
    Type: AWS::GameLift::Fleet
    Properties:
      BuildId: !Ref BuildResource
      CertificateConfiguration:
        CertificateType: DISABLED
      Description: Description of my Game Fleet3
      DesiredEc2Instances: 1
      EC2InboundPermissions:
        - FromPort: 1234
          ToPort: '134'
          IpRange: 0.0.0.0/24
          Protocol: TCP
        - FromPort: '1356'
          ToPort: 1578
          IpRange: 192.168.0.0/24
          Protocol: UDP

{
  "Resources": {
    "FleetResource1": {
      "Type": "AWS::GameLift::Fleet",
      "Properties": {
        "EC2InboundPermissions": [
          {
            "FromPort": "1234",
            "ToPort": "134",
            "IpRange": "0.0.0.0/24",
            "Protocol": "TCP"
          },
          {
            "FromPort": 1356,
            "ToPort": 1578,
            "IpRange": "192.168.0.0/24",
            "Protocol": "UDP"
          }
        ],
        "BuildId": "BuildResource",
        "CertificateConfiguration": {
          "CertificateType": "DISABLED"
        },
        "Description": "Description of my Game Fleet1",
        "DesiredEc2Instances": 1
      }
    },
    "FleetResource3": {
      "Type": "AWS::GameLift::Fleet",
      "Properties": {
        "BuildId": "BuildResource",
        "CertificateConfiguration": {
          "CertificateType": "DISABLED"
        },
        "Description": "Description of my Game Fleet3",
        "DesiredEc2Instances": 1,
        "EC2InboundPermissions": [
          {
            "FromPort": 1234,
            "ToPort": "134",
            "IpRange": "0.0.0.0/24",
            "Protocol": "TCP"
          },
          {
            "FromPort": "1356",
            "ToPort": 1578,
            "IpRange": "192.168.0.0/24",
            "Protocol": "UDP"
          }
        ]
      }
    }
  }
}