Piecemaker

Description

There is a secret hidden deep in the DC universe. It’s a conspiracy… Or is it?

• Author: tcs
• Attachments: piecemaker.tar.gz

Solution

0x1 initial puzzle

Extracting the files from the given archive, we get tons of puzzle pieces. The task seems simple, put it together. With a bit of python magic, we can remove most of the green background, and put the puzzle pieces together using GIMP for example.

from PIL import Image
import glob
from pwn import *

images = glob.glob("../*.jpg")

pr = log.progress("Status")

count = 0

for image in images:
    img = Image.open(image)
    img = img.convert("RGBA")
    datas = img.getdata()


    newData = []
    for item in datas:
        if item[1] > 240 and item[2] < 10:
            newData.append((255, 255, 255, 0))
        else:
            newData.append(item)

    img.putdata(newData)
    img.save(f"{count}.png", "PNG")
    count += 1
    pr.status(f'{count / len(images) * 100}')

pr.success("Done")

This had me puzzled (haHa) for a while, but after googling some languages commonly used in CTFs, I found out about Klingon. Using some ABCs found online I could decode the following text on the image:

this is christopher smith known as p
eacemaker i love formula one aka f1
as well as f2 and f3 but you know wh
at would be even better f5 i also lo
ve java but scripting should be bann
ed the whole password is in gold

i cherish peace with all my heart
i dont care how many men women and
children i need to kill to get it

This next part required a hint from the author, since everyone was stuck on this part for a moment. The hint came:

We've just received an urgent transmission from Peacemaker telling us his favorite dinosaur is stegosaurus.

Alright, a stego challenge, nothing I haven’t knew before. But this finally led me to google for stego f5 java insead of f5 java. And trust me, it made all the diference (Why would you name a firewall company after a stego tool or vice versa???). I wrote a bash script to extract whatever is hidden inside the images (just so you see other things on this blog besides python scripts):

#!/bin/bash

declare -i c=0

mkdir -p out/

for f in piecemaker/*.jpg
do
	java -jar f5.jar x -e out/$c.gz $f -p "i cherish peace with all my heart i dont care how many men women and children i need to kill to get it";
	c+=1	
done

cd out/
rm 91.gz 92.gz 93.gz 94.gz 95.gz 96.gz 97.gz 98.gz 99.gz 100.gz 101.gz 102.gz
rm 103.gz 104.gz 105.gz 106.gz 107.gz 108.gz 109.gz 110.gz 111.gz

for file in *.gz
do
	tar zxvf $file
done

0x2 joyride to the flag

At this point, I know, I had the flag… there was only a small problem, again, it was in pieces. Luckily the creator didn’t make any more matryoshkas, or else I would have been sitting here for quite some time. Piece by piece, I put together the puzzle, which contained the flag as an image:

cd22{HIDDEN}

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