mitmproxy for modifying js on-the-fly

README.md

ProxyJS

NodeJS proxy with JS intrumentation

Requirements

modules:

• python mitmproxy
• esprima
• cheerio

Features

• mitmproxy
• modified target response on the fly
• instrument dom-based XSS

jsproxy.js

var zerorpc = require("zerorpc");

var server = new zerorpc.Server({
    process: function (data, reply) {
        // Init

        var _isHTML = false,
            _isJS = false;

        var _contentType = "";

        var _headers = JSON.parse(data).headers;
        var _content = JSON.parse(data).content;

        var processedContent = "";

        // Methods

        var initProcess = function () {

            if (_headers['Content-Type']) {
                _contentType = _headers['Content-Type'];

                if (_contentType.match(/javascript/)) {
                    _isJS = true;
                } else if (_contentType.match(/text\/html/)) {
                    _isHTML = true;
                }
            }

            if (_isHTML || _isJS) {

                processedContent = new Buffer(0);
            }

        };

        var _instrumentJS = function (strJS) {
            return strJS;
        };

        var _instrumentHTML = function (strHTML) {
            return strHTML;
        };

        /*
         Main process
        */
        initProcess();


        if (_isJS) {
            processedContent = _instrumentJS(_content);
        } else if (_isHTML) {
            processedContent = _instrumentHTML(_content);
        } else {
            processedContent = _content;
        }

        reply(null, "Hello, " + processedContent, false);

    }
});
<<<<<<< HEAD
server.bind("tcp://127.0.0.1:3000");
=======
server.bind("tcp://127.0.0.1:3000");
>>>>>>> b7c9613e88cf2c043fa5dfafcc0d8429720923d4

reponse_modifying.py

from libmproxy.models import decoded
from re import search

import zerorpc
import json


buffer_size = 4096


def instrument(data):
    ret = ""
    c = zerorpc.Client()
    c.connect("tcp://127.0.0.1:3000")

    return c.process(data)


def response(context, flow):
    with decoded(flow.response):  # automatically decode gzipped responses.
        headers = flow.response.headers.fields
        contentType = flow.response.headers.get('Content-Type')
        content = flow.response.content

        isProcess = False

        if search("text\/html",contentType) or search("javascript", contentType):
            print "Process... "
            mes = json.dumps({"headers": headers, "content": content})
            content = instrument(mes)

        flow.response.content = content