ec2-public-ip: Public IP on EC2 Instances

id: ec2-public-ip
info:
  name: Public IP on EC2 Instances
  author: princechaddha
  severity: unknown
  description: |
    Ensures Amazon EC2 instances, especially backend ones, do not use public IP addresses to minimize Internet exposure.
  impact: |
    Instances with public IP addresses are more vulnerable to Internet-based threats, compromising network security.
  remediation: |
    Restrict public IP assignment for EC2 instances, particularly for backend instances. Use private IPs and manage access via AWS VPC and security groups.
  reference:
    - https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-instance-addressing.html#concepts-public-addresses
  metadata:
    max-request: 2
  tags: cloud,devops,aws,amazon,ec2,aws-cloud-config
variables:
  region: "us-east-1"

flow: |
  code(1)
  for(let InstancesName of iterate(template.instances)){
    set("ec2instance", InstancesName)
    code(2)
  }

self-contained: true
code:
  - engine:
      - sh
      - bash
    source: |
      aws ec2 describe-instances --region $region --output json --query 'Reservations[*].Instances[*].InstanceId'

    extractors:
      - type: json
        name: instances
        internal: true
        json:
          - '.[].[]'

  - engine:
      - sh
      - bash
    source: |
         aws ec2 describe-instances --region $region --instance-ids $ec2instance --query "Reservations[*].Instances[*].NetworkInterfaces[*].Association.IpOwnerId[] | []"

    matchers:
      - type: word
        words:
          - "amazon"

    extractors:
      - type: dsl
        dsl:
          - '"The Amazon Instance " + ec2instance + " uses public IP addresses"'
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