Skip to content
Nuclei Templates

Unrestricted DNS Access in EC2

ID: ec2-unrestricted-dns

Severity: critical

Author: princechaddha

Tags: cloud,devops,aws,amazon,ec2,aws-cloud-config

Description

Section titled “Description”

Checks for inbound rules in Amazon EC2 security groups that allow unrestricted access (0.0.0.0/0 or ::/0) on TCP/UDP port 53, which can expose DNS servers to potential attacks.

YAML Source

Section titled “YAML Source”
id: ec2-unrestricted-dns
info:
  name: Unrestricted DNS Access in EC2
  author: princechaddha
  severity: critical
  description: |
    Checks for inbound rules in Amazon EC2 security groups that allow unrestricted access (0.0.0.0/0 or ::/0) on TCP/UDP port 53, which can expose DNS servers to potential attacks.
  impact: |
    Allowing unrestricted access to DNS services can lead to DNS spoofing, DDoS attacks, and unauthorized access to internal networks.
  remediation: |
    Restrict the inbound rules for TCP/UDP port 53 in EC2 security groups to known, trusted IPs only. Ensure security group rules are tightly controlled and monitored.
  reference:
    - https://docs.aws.amazon.com/vpc/latest/userguide/VPC_SecurityGroups.html#SecurityGroupRules
  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=53 Name=ip-permission.to-port,Values=53 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 TCP port 53"'
# digest: 4b0a004830460221008233370a72ac39d30f1ee1f45b7463c5c185e4dc358c70084bab7c8666bc7c9f022100bb44c563dde300e18db8520fe30bc8e0b61b66002a09f78c3d8dee78042eaf81:922c64590222798bb761d5b6d8e72950

Guide to check the vulnerabilities

Section titled “Guide to check the vulnerabilities”

This template is used to detect vulnerabilities in web applications. It can be used with the Nuclei tool to scan for specific patterns or behaviors.

Terminal window
$ nuclei -u "URL" -t "cloud/aws/ec2/ec2-unrestricted-dns.yaml"

View on Github