el-picasso

Item	Value
Category	Reverse Engineering
Difficulty	Hard

Challenge Overview

Allowing IDA Pro to view more graph functions was the solution to this challenge.

Options -> General -> Graph -> Max number of nodes: 9999999

After pressing F5 we get this weird functions.

weird functions

Exploitation

However, once we zoom out we get something crazy.

qr code

A QR Code.

I managed to retrieve it using this python script which reverse the white color to black and all other colors to white (to get something closer to a QR code, like a dotted one).

from PIL import Image

img = Image.open("qrcode.png").convert("RGB")
pixels = img.load()

width, height = img.size

for y in range(height):
    for x in range(width):
        r, g, b = pixels[x, y]

        if (r, g, b) == (255, 255, 255):
            pixels[x, y] = (0, 0, 0)  
        else:
            pixels[x, y] = (255, 255, 255) 

img.save("qrcode_blackwhite")
img.show()

This returns the following picture:

it's clearly way better so we just have to mess with it until we get something readable.

Final Result

Then AI (GPT 5.2 Thinking) got the correct QR which can be decoded using a lot of tools or python libraries (cv2, pillow, etc.)

made by k0d