Security Groups Allows Unrestricted Outbound Traffic

• Query id: 66f2d8f9-a911-4ced-ae27-34f09690bb2c
• Query name: Security Groups Allows Unrestricted Outbound Traffic
• Platform: CloudFormation
• Severity: High
• Category: Networking and Firewall
• URL: Github

Description

No security group should allow unrestricted egress access
Documentation

Code samples

Code samples with security vulnerabilities

Positive test num. 1 - yaml file

Parameters:
  KeyName:
    Description: The EC2 Key Pair to allow SSH access to the instance
    Type: 'AWS::EC2::KeyPair::KeyName'
Resources:
  Ec2Instance:
    Type: 'AWS::EC2::Instance'
    Properties:
      SecurityGroups:
        - !Ref InstanceSecurityGroup
        - MyExistingSecurityGroup
      KeyName: !Ref KeyName
      ImageId: ami-7a11e213
  InstanceSecurityGroup:
    Type: 'AWS::EC2::SecurityGroup'
    Properties:
      GroupDescription: Enable SSH access via port 22
      SecurityGroupIngress:
        - IpProtocol: tcp
          FromPort: '22'
          ToPort: '22'
          CidrIp: 0.0.0.0/0
      SecurityGroupEgress:
        - IpProtocol: ALL
          FromPort: '22'
          ToPort: '22'
          CidrIp: 0.0.0.0/0

Positive test num. 2 - json file

{
  "Parameters": {
    "KeyName": {
      "Description": "The EC2 Key Pair to allow SSH access to the instance",
      "Type": "AWS::EC2::KeyPair::KeyName"
    }
  },
  "Resources": {
    "Ec2Instance": {
      "Type": "AWS::EC2::Instance",
      "Properties": {
        "ImageId": "ami-7a11e213",
        "SecurityGroups": [
          "InstanceSecurityGroup",
          "MyExistingSecurityGroup"
        ],
        "KeyName": "KeyName"
      }
    },
    "InstanceSecurityGroup": {
      "Properties": {
        "SecurityGroupIngress": [
          {
            "CidrIp": "0.0.0.0/0",
            "IpProtocol": "tcp",
            "FromPort": "22",
            "ToPort": "22"
          }
        ],
        "SecurityGroupEgress": [
          {
            "IpProtocol": "ALL",
            "FromPort": "22",
            "ToPort": "22",
            "CidrIp": "0.0.0.0/0"
          }
        ],
        "GroupDescription": "Enable SSH access via port 22"
      },
      "Type": "AWS::EC2::SecurityGroup"
    }
  }
}

Code samples without security vulnerabilities

Negative test num. 1 - yaml file

Parameters:
  KeyName:
    Description: The EC2 Key Pair to allow SSH access to the instance
    Type: 'AWS::EC2::KeyPair::KeyName'
Resources:
  Ec2Instance:
    Type: 'AWS::EC2::Instance'
    Properties:
      SecurityGroups:
        - !Ref InstanceSecurityGroup
        - MyExistingSecurityGroup
      KeyName: !Ref KeyName
      ImageId: ami-7a11e213
  InstanceSecurityGroup:
    Type: 'AWS::EC2::SecurityGroup'
    Properties:
      GroupDescription: Enable SSH access via port 22
      SecurityGroupIngress:
        - IpProtocol: tcp
          FromPort: '22'
          ToPort: '22'
          CidrIp: 0.0.0.0/0
      SecurityGroupEgress:
        - IpProtocol: tcp
          FromPort: '22'
          ToPort: '22'
          CidrIp: 0.0.0.0/0

Negative test num. 2 - json file

{
  "Parameters": {
    "KeyName": {
      "Description": "The EC2 Key Pair to allow SSH access to the instance",
      "Type": "AWS::EC2::KeyPair::KeyName"
    }
  },
  "Resources": {
    "Ec2Instance": {
      "Type": "AWS::EC2::Instance",
      "Properties": {
        "SecurityGroups": [
          "InstanceSecurityGroup",
          "MyExistingSecurityGroup"
        ],
        "KeyName": "KeyName",
        "ImageId": "ami-7a11e213"
      }
    },
    "InstanceSecurityGroup": {
      "Type": "AWS::EC2::SecurityGroup",
      "Properties": {
        "GroupDescription": "Enable SSH access via port 22",
        "SecurityGroupIngress": [
          {
            "IpProtocol": "tcp",
            "FromPort": "22",
            "ToPort": "22",
            "CidrIp": "0.0.0.0/0"
          }
        ],
        "SecurityGroupEgress": [
          {
            "CidrIp": "0.0.0.0/0",
            "IpProtocol": "tcp",
            "FromPort": "22",
            "ToPort": "22"
          }
        ]
      }
    }
  }
}