Prog
Back to kindergarten ! Here is a puzzle to solve. Unfortunalty the other kids din't take good care of it, and the pieces are worn out...
Format : Hero{flag}
Author : Log_s
- pieces.zip
Each image is corrupted. If you look closer, 2 bytes of the well known PNG header were alterned. If you patch them by hand, you'll see a valid PNG with a fair amount of green on it, 15x15 px big.
Last thing is to figure out how to put the pieces together. If we consider the altered bytes as coordinates, we could write the following script :
#!/usr/bin/env python3
from PIL import Image
from os import listdir, system
import sys
DIR = "pieces/"
size = 15
files = listdir(DIR)
matrix = []
print("[*] Finding max values in x and y")
x_max = 0
y_max = 0
for file in files:
f = open(DIR + file, "rb")
f.seek(2)
x = int.from_bytes(f.read(1), byteorder='big')
y = int.from_bytes(f.read(1), byteorder='big')
if x > x_max:
x_max = x
if y > y_max:
y_max = y
# If the maximum index is 9, the size is 10
x_max += 1
y_max += 1
print("[*] Initializing the matrix containing the file names")
for y in range(y_max):
matrix.append([])
for x in range(x_max):
matrix[y].append("")
print("[*] Storing the files and patching them")
print("|-------10%-------20%-------30%-------40%-------50%-------60%-------70%-------80%-------90%------100%|\n ", end="")
last = 0
for i, file in enumerate(files):
f = open(DIR + file, "rb")
f.seek(2)
x = int.from_bytes(f.read(1), byteorder='big')
y = int.from_bytes(f.read(1), byteorder='big')
system("./patch " + DIR + file + " 0x4E 2")
system("./patch " + DIR + file + " 0x47 3")
matrix[y][x] = DIR + file
if (int(100*i/len(files)) > last):
last = int(100*i/len(files))
sys.stdout.write("=")
sys.stdout.flush()
print("\n[*] Reconstruct the initial image")
flag = Image.new('RGB', (x_max*size, y_max*size))
for y in range(y_max):
for x in range(x_max):
x_image = x * size
y_image = y * size
img = Image.open(matrix[y][x])
flag.paste(img, (x_image, y_image))
flag.save("flag.png")
print("[+] Done")The patch binary I am using is just a little C program I wrote for fast little patches. It may not be the fastest solution calling os.system() so many times, but I had the binary ready so it saved me some time.
Hero{PuZzzZZzzzZzzzzL3}