I'm doing a MitM attack homework. It requires me to change the HTTP payload (adding script tags to the HTML content). I was able to inject the script but I found the content received on the user's side is always cut short. I then realized that the Content-Length field in the HTTP header wasn't increased to accommodate the longer HTTP data. I tried to set the Content-Length header this way. new_packet.show() prints fine, showing the updated Content-Length. But when I checked on the client side it still sees the original Content-Length as if nothing was changed. res: HTTPResponse = tcp[HTTPResponse] res.fields["Content_Length"] = content_len new_packet = IP(src=ip.src, dst=ip.dst) / tcp new_packet.show() send(new_packet) I checked other related answers here and on scapy's github issues page but the discussions seem to be very outdated. Has anyone successfully changed the header fields this way? Am I supposed to use another method to modify header fields? Continue reading...
