ec2-sg-egress-open: Open Egress in EC2 Security Group

id: ec2-sg-egress-open
info:
  name: Open Egress in EC2 Security Group
  author: princechaddha
  severity: high
  description: |
    Checks for unrestricted outbound/egress rules in Amazon EC2 security groups, highlighting potential over-permissive configurations.
  impact: |
    Allows unrestricted outbound traffic from EC2 instances, increasing the risk of data exfiltration and malicious external communications.
  remediation: |
    Restrict egress traffic in EC2 security groups to only necessary IP addresses and ranges, adhering to the Principle of Least Privilege.
  reference:
    - https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-security-groups.html#sg-rules
  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 --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[*].IpPermissionsEgress[]'

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

    extractors:
      - type: dsl
        dsl:
          - '"Amazon EC2 security group(s) " + groupid + " allows unrestricted outbound traffic"'
# digest: 4a0a00473045022100fab25cd451861c61bd395688f05669575673619b29cf554770dcea2403af9a9a022073e8fc297a89cbc2c42c6be3765db214bd465ac621135cb152a8c2e0cc97b346:922c64590222798bb761d5b6d8e72950