Unknown Port Exposed To Internet

• Query id: 829ce3b8-065c-41a3-ad57-e0accfea82d2
• Query name: Unknown Port Exposed To Internet
• Platform: CloudFormation
• Severity: High
• Category: Networking and Firewall
• URL: Github

Description

AWS Security Group should not have an unknown port exposed to the entire Internet
Documentation

Code samples

Code samples with security vulnerabilities

Positive test num. 1 - yaml file

Resources:
  InstanceSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
        GroupDescription: Expose unknown port to client host
        VpcId:
          Ref: myVPC
        SecurityGroupIngress:
        - IpProtocol: tcp
          FromPort: 23
          ToPort: 25
          CidrIp: 0.0.0.0/0

Positive test num. 2 - json file

{
  "Resources": {
    "InstanceSecurityGroup": {
      "Type": "AWS::EC2::SecurityGroup",
      "Properties": {
        "GroupDescription": "Expose unknown port to client host",
        "VpcId": {
          "Ref": "myVPC"
        },
        "SecurityGroupIngress": [
          {
            "IpProtocol": "tcp",
            "FromPort": 110,
            "ToPort": 119,
            "CidrIp": "0.0.0.0/0"
          }
        ]
      }
    }
  }
}

Code samples without security vulnerabilities

Negative test num. 1 - yaml file

Resources:
  InstanceSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
        GroupDescription: Expose known ports to client host
        VpcId:
          Ref: myVPC
        SecurityGroupIngress:
        - IpProtocol: tcp
          FromPort: 20
          ToPort: 23
          CidrIp: 0.0.0.0/0

Negative test num. 2 - json file

{
  "Resources": {
    "InstanceSecurityGroup": {
      "Type": "AWS::EC2::SecurityGroup",
      "Properties": {
        "GroupDescription": "Expose known port to client host",
        "VpcId": {
          "Ref": "myVPC"
        },
        "SecurityGroupIngress": [
          {
            "IpProtocol": "tcp",
            "FromPort": 80,
            "ToPort": 80,
            "CidrIp": "0.0.0.0/0"
          }
        ]
      }
    }
  }
}