main.js

"use strict";

var randomstring = require("randomstring");
var express = require("express");
var {VM} = require("vm2");
var fs = require("fs");

var app = express();
var flag = require("./config.js").flag

app.get("/", function (req, res) {
    res.header("Content-Type", "text/plain");

    /*    Orange is so kind so he put the flag here. But if you can guess correctly :P    */
    eval("var flag_" + randomstring.generate(64) + " = \"hitcon{" + flag + "}\";")
    if (req.query.data && req.query.data.length <= 12) {
        var vm = new VM({
            timeout: 1000
        });
        console.log(req.query.data);
        res.send("eval ->" + vm.run(req.query.data));
    } else {
        res.send(fs.readFileSync(__filename).toString());
    }
});

app.listen(3000, function () {
    console.log("listening on port 3000!");
});