id: elasticbeanstalk-takeover

info:
  name: ElasticBeanstalk Subdomain Takeover Detection
  author: philippedelteil,rotemreiss,zy9ard3,joaonevess
  severity: high
  description: ElasticBeanstalk subdomain takeover detected. A subdomain takeover occurs when an attacker gains control over a subdomain of a target domain. Typically, this happens when the subdomain has a canonical name (CNAME) in the Domain Name System (DNS), but no host is providing content for it.
  reference:
    - https://github.com/EdOverflow/can-i-take-over-xyz/issues/147
    - https://twitter.com/payloadartist/status/1362035009863880711
    - https://www.youtube.com/watch?v=srKIqhj_ki8
  classification:
    cvss-metrics: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
    cvss-score: 7.2
    cwe-id: CWE-404
  metadata:
    max-request: 1
    comments: |
      Only CNAMEs with region specification are hijackable.
      You need to claim the CNAME in AWS portal (https://aws.amazon.com/) or via AWS CLI to confirm the takeover.
      Do not report this without claiming the CNAME.
      CLI command to verify the availability of the environment:
      aws elasticbeanstalk check-dns-availability --region {AWS_REGION} --cname-prefix {CNAME_PREFIX}
      For example:
      CNAME - 2rs3c.eu-west-1.elasticbeanstalk.com
      Command - aws elasticbeanstalk check-dns-availability --region eu-west-1 --cname-prefix 2rs3c
  tags: dns,takeover,aws

dns:
  - name: "{{FQDN}}"
    type: A

    matchers-condition: and
    matchers:
      - type: regex
        regex:
          - CNAME\t[a-z0-9_-]*\.(us|af|ap|ca|eu|me|sa|il)\-(north|east|west|south|northeast|southeast|central)\-[1-9]+\.elasticbeanstalk\.com

      - type: word
        words:
          - NXDOMAIN

    extractors:
      - type: dsl
        dsl:
          - cname

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