ec2-sg-ingress: Unrestricted Access on Uncommon EC2 Ports

id: ec2-sg-ingress
info:
  name: Unrestricted Access on Uncommon EC2 Ports
  author: princechaddha
  severity: high
  description: |
    Ensure Amazon EC2 security groups do not allow unrestricted access (0.0.0.0/0, ::/0) on uncommon ports, protecting against brute force attacks on EC2 instances.
  impact: |
    Unrestricted ingress on uncommon ports increases the risk of unauthorized access and potential brute force attacks on EC2 instances.
  remediation: |
    Restrict access to uncommon ports in EC2 security groups, permitting only necessary traffic and implementing stringent access controls.
  reference:
    - https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/security-group-rules-reference.html
  metadata:
    max-request: 2
  tags: cloud,devops,aws,amazon,ec2,aws-cloud-config
variables:
  region: "us-east-1"

flow: |
  code(1)
  for(let SecurityGroup of iterate(template.securitygroups)){
    set("groupid", SecurityGroup)
    code(2)
  }

self-contained: true
code:
  - engine:
      - sh
      - bash
    source: |
      aws ec2 describe-security-groups --region $region --filters Name=ip-permission.cidr,Values='0.0.0.0/0' --output json --query 'SecurityGroups[*].GroupId'

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

  - engine:
      - sh
      - bash
    source: |
         aws ec2 describe-security-groups --region $region --group-ids $groupid --query 'SecurityGroups[*].IpPermissions[]'

    matchers:
      - type: word
        words:
          - "0.0.0.0/0"
          - "::/0"

    extractors:
      - type: dsl
        dsl:
          - '"Amazon EC2 security group(s) " + groupid + " allows unrestricted inbound traffic"'
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