ec2-unrestricted-netbios: Unrestricted NetBIOS Access in EC2

id: ec2-unrestricted-netbios
info:
  name: Unrestricted NetBIOS Access in EC2
  author: princechaddha
  severity: critical
  description: |
    Checks for inbound rules in Amazon EC2 security groups that allow unrestricted access on TCP port 139 and UDP ports 137 and 138, increasing the risk of unauthorized access and potential security breaches.
  impact: |
    Unrestricted NetBIOS access can expose EC2 instances to network-based attacks, compromising data integrity and system availability.
  remediation: |
    Restrict access to TCP port 139 and UDP ports 137 and 138 in EC2 security groups. Implement strict access control based on the principle of least privilege.
  reference:
    - https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-security-groups.html
  tags: cloud,devops,aws,amazon,ec2,aws-cloud-config

variables:
  region: "us-east-1"

self-contained: true
code:
  - engine:
      - sh
      - bash
    source: |
      aws ec2 describe-security-groups --region $region --filters Name=ip-permission.from-port,Values=137,138,139 Name=ip-permission.to-port,Values=137,138,139 Name=ip-permission.cidr,Values='0.0.0.0/0' --output json --query 'SecurityGroups[*].GroupId'

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

      - type: dsl
        dsl:
          - 'securitygroup + " security group(s) alows unrestricted access (0.0.0.0/0 or ::/0) on ports 137, 138 or 139"'
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