Logic Munchers

Elf: Noel Boetie
Direct link: logicmunchers website
Objective: Slot Machine Investigation

Request

Noel Boetie

Hello there! Noel Boetie here. We're all so glad to have you attend KringleCon IV and work on the Holiday Hack Challenge!
I'm just hanging out here by the Logic Munchers game.
You know... logic: that thing that seems to be in short supply at the tower on the other side of the North Pole?
Oh, I'm sorry. That wasn't terribly kind, but those frosty souls do confuse me...
Anyway, I'm working my way through this Logic Munchers game.
A lot of it comes down to understanding boolean logic, like True And False is False, but True And True is True.
It can get a tad complex in the later levels.
I need some help, though. If you can show me how to complete a stage in Potpourri at the Intermediate (Stage 3) or higher, I'll give you some hints for how to find vulnerabilities.
Specifically, I'll give you some tips in finding flaws in some of the web applications I've heard about here at the North Pole, especially those associated with slot machines!

Hints

Boolean Logic

There are lots of special symbols for logic and set notation. This one covers AND, NOT, and OR at the bottom.

AND, OR, NOT, XOR

This might be a handy reference too.

Solution

To unlock the achievement we need to complete a stage in Potpourri on Intermediate or higher. We can either play the game as intended and learn about boolean logic or we can cheat. Each grid is represented by a JavaScript variable named challenges which contains both the statement shown in each cell as well as the associated true or false result.

The chompy.js game code contains a checkWin() function which iterates over this challenges variable and checks if any items are still set to true (i.e., still need to be chomped) and if not, levels up the game. Start a stage in Potpourri on Intermediate or higher and paste the below JavaScript code in your web browser's console. This will set all item results in challenges to false (line 3), satisfying the checkWin() function, and level up the game.

for (var col = 0; col < challenges.length; col++) {
    for (var cell = 0; cell < challenges[col].length; cell++) {
        challenges[col][cell][1] = false;
    }
}
checkWin()

The autoplay_chompers.js script below takes this a step further by adding a timer that repeats this logic for each new level. The biggest difference with the code snippet above is that it more closely mimics a user playing the game by searching for items in challenges that are set to true and calling a chomp() function on those cells.

autoplay_chompers.js

// Modified chomp function that checks the cell at position (x,y)
function chomp(x, y) {
    if (challenges[x][y][0] != "") {
        // Clear the cell
        document.getElementById(x + ',' + y).innerHTML = "";
        if (challenges[x][y][1]) {
            // Update the score
            score += 100;
            document.getElementById("score").innerHTML = "<h2>" + score + "</h2>";
        } else {
            // Leave this in as a sanity check
            wigwags("Oh no! Ate a wrong answer!")
        }
    }
    challenges[x][y] = [[],[]]; 
    checkWin();
}             

// Play the level by chomping each cell containing a true statement
function playLevel() {
    for (var col = 0; col < challenges.length; col++) {
        for (var cell = 0; cell < challenges[col].length; cell++) {
            if (challenges[col][cell][1] == true) {chomp(col,cell);}
        }
    }
}

// Call playLevel() every 2 seconds
setInterval(playLevel, 2000); 

The chomp() function will verify that the cell's result is in fact true and run through the game mechanics like updating the score, clearing out the cell, and calling checkWin() to level up the game. To use the script, start a new game, paste the contents of autoplay_chompers.js in your web browser's console, sit back, and enjoy the show.

Response

Noel Boetie

Wow - amazing score! Great work!
So hey, those slot machines. It seems that in his haste, Jack bought some terrible hardware.
It seems they're susceptible to parameter tampering.
You can modify web request parameters with an intercepting proxy or tools built into Firefox.