ELB With Security Group Without Outbound Rules

• Query id: 01d5a458-a6c4-452a-ac50-054d59275b7c
• Query name: ELB With Security Group Without Outbound Rules
• Platform: CloudFormation
• Severity: Medium
• Category: Networking and Firewall
• URL: Github

Description

An AWS Elastic Load Balancer (ELB) shouldn´t have security groups without outbound rules
Documentation

Code samples

Code samples with security vulnerabilities

Positive test num. 1 - yaml file

AWSTemplateFormatVersion: 2010-09-09
Resources:
    sgwithoutegress:
        Type: AWS::EC2::SecurityGroup
        Properties:
            GroupDescription: Limits security group egress traffic
    MyLoadBalancer:
        Type: AWS::ElasticLoadBalancing::LoadBalancer
        Properties:
            SecurityGroups:
            -   sgwithoutegress

Positive test num. 2 - json file

{
  "AWSTemplateFormatVersion": "2010-09-09T00:00:00Z",
  "Resources": {
    "sgwithoutegress": {
      "Type": "AWS::EC2::SecurityGroup",
      "Properties": {
        "GroupDescription": "Limits security group egress traffic"
      }
    },
    "MyLoadBalancer": {
      "Type": "AWS::ElasticLoadBalancing::LoadBalancer",
      "Properties": {
        "SecurityGroups": [
          "sgwithoutegress"
        ]
      }
    }
  }
}

Code samples without security vulnerabilities

Negative test num. 1 - yaml file

AWSTemplateFormatVersion: 2010-09-09
Resources:
    sgwithegress:
        Type: AWS::EC2::SecurityGroup
        Properties:
            GroupDescription: Limits security group egress traffic
            SecurityGroupEgress:
            -   IpProtocol: tcp
                FromPort: 80
                ToPort: 80
                CidrIp: 0.0.0.0/0
    MyLoadBalancer:
        Type: AWS::ElasticLoadBalancing::LoadBalancer
        Properties:
            SecurityGroups:
            -   sgwithegress

Negative test num. 2 - json file

{
  "AWSTemplateFormatVersion": "2010-09-09T00:00:00Z",
  "Resources": {
    "sgwithegress": {
      "Properties": {
        "GroupDescription": "Limits security group egress traffic",
        "SecurityGroupEgress": [
          {
            "IpProtocol": "tcp",
            "FromPort": 80,
            "ToPort": 80,
            "CidrIp": "0.0.0.0/0"
          }
        ]
      },
      "Type": "AWS::EC2::SecurityGroup"
    },
    "MyLoadBalancer": {
      "Type": "AWS::ElasticLoadBalancing::LoadBalancer",
      "Properties": {
        "SecurityGroups": [
          "sgwithegress"
        ]
      }
    }
  }
}